MS handgun caliber

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Seraphic
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MS handgun caliber

Post by Seraphic » Thu Sep 19, 2013 8:56 pm

What do you think is a proper caliber for a MS handgun? I know that the typical convention is to increase the caliber by a factor of 10 from a human scale weapon.

However, that makes me wonder about how conventional handguns have much larger calibers than rifles. Most rifles in Gundam seem to hover around 100mm, right? By the 10x scale, a mobile suit's battle rifle would be something more like 60mm or so, but they are twice that.

In short, should a MS handgun bullet have a caliber greater or lesser than 100mm? What are some existing examples? If the bullets were to be caseless, how would this affect size restrictions on the ammunition?

As an example, I know that a Leo's rifle is 105mm, and its "handgun" is just the same gun with most of the barrel cut off of it. =3
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toysdream
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Re: MS handgun caliber

Post by toysdream » Fri Sep 20, 2013 2:38 pm

Actually, we had a recent thread on a similar topic...

It's true that human-scale handguns generally have higher calibers than rifles - rifle bullets are normally longer and thinner. But as I noted in the previous thread, when you actually look at the dimensions of the Gundam weapons, their magazines and cartridge slots, representations of them in the model kits, etc, it seems pretty clear that the rifle rounds pretty much are scaled up ten times from human weapons and that their listed calibers are over-estimates.

In fact, the rounds in the Zaku's "120mm" machine gun are pretty much ten times the size of a 7.62mm rifle round. So it seems like the listed caliber should really correspond to the diameter of the entire round, rather than the bullet itself. A similar claim has been made for the GM Rifle used in Gundam 0083 - that this weapon fires 90mm bullets when configured as a handgun, and 55.6mm bullets in a 90mm caseless block when configured as a rifle.

In the previous thread, I also noted that the MMP-80 Zaku machine gun used in Gundam 0080 and 0083 legitimately appears to fire 90mm bullets. It's normally said that this weapon has higher firepower than the original Zaku machine gun because it fires higher-velocity, lower-caliber rounds, but this suggests that its bullets are actually higher-caliber than the original - it's basically a scaled-up 90mm submachine gun, while the original is more like a scaled-up 7.62mm rifle.

-- Mark

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Re: MS handgun caliber

Post by Nebfer » Fri Sep 27, 2013 2:26 am

toysdream wrote:Actually, we had a recent thread on a similar topic...

It's true that human-scale handguns generally have higher calibers than rifles - rifle bullets are normally longer and thinner. But as I noted in the previous thread, when you actually look at the dimensions of the Gundam weapons, their magazines and cartridge slots, representations of them in the model kits, etc, it seems pretty clear that the rifle rounds pretty much are scaled up ten times from human weapons and that their listed calibers are over-estimates.

In fact, the rounds in the Zaku's "120mm" machine gun are pretty much ten times the size of a 7.62mm rifle round. So it seems like the listed caliber should really correspond to the diameter of the entire round, rather than the bullet itself. A similar claim has been made for the GM Rifle used in Gundam 0083 - that this weapon fires 90mm bullets when configured as a handgun, and 55.6mm bullets in a 90mm caseless block when configured as a rifle.

In the previous thread, I also noted that the MMP-80 Zaku machine gun used in Gundam 0080 and 0083 legitimately appears to fire 90mm bullets. It's normally said that this weapon has higher firepower than the original Zaku machine gun because it fires higher-velocity, lower-caliber rounds, but this suggests that its bullets are actually higher-caliber than the original - it's basically a scaled-up 90mm submachine gun, while the original is more like a scaled-up 7.62mm rifle.

-- Mark
An interesting off shoot of this would help deal with the weight of the weapons and their ammo.

Using current real world weights for a 120mm based weapon the gun would easily be 2.5 to 4 tons, as current real world tank guns weigh that much (but do not have do deal with cooling in space and automatic reloading and their recoil). The Ammo alone would weight at roughly 2 tons to 3 tons or over 5 tons if we use WW2 era ammo weights with magazine (assuming 100 rounds is actually accurate). As such a loaded weapon could weigh anywhere from 4ish tons to as much as 10 or so tons. I do not think it would take to much effort to see an issue with a "10" ton MG with a most mobile suits listed specs...

On the other hand a 70 to 80mm based weapon with a cartridge case diameter of 120mm (hence it being a 120mm). Their are not many modern 75mm guns in todays use but I do know WW2 era tank guns of that caliber where around 1 ton or so (The Panthers gun is roughly a ton by it self (including breach, and recoil sys I believe), the 76mm OTO-Melara gun on many naval ships of today has a gun tube of .75 tons -sans breach, recoil and mounting I believe), some improved metallurgy, space adaptations and automatic firing capability's and one could see a 1 to 1.5 ton automatic cannon (2 tons at most). The Ammo even using WW2 era weights would weigh under 1.75 tons, with more modern style ammo one could get it to be around a ton with the magazine.
IIRC the zakus MG has a barrel of around 5 meters in length which would put in the range of the OTO-Melara which is a 62 caliber gun (with current models pulling at 125ish RPM).

As such a 76mm based gun with a cartridge case diameter of 120mm easily can be under 4 tons with a loaded magazine, likely around 2.5 to 3 tons loaded. Leaving enough room for a heat hawk... with the supposed MS specs...

It also partly solves the odd issue of why a seemingly smaller caliber of 90mm was considered to be better vs mobile suits and what naught than a 120mm one... It's not actually a 120mm gun but 70-80mm with a case of 120mm. With the "90mm" not have any necking to it's case so it's also 90mm. Though their is the issue of if true then the 90mm even though being bigger is seemingly based off a pistol round and not a rifle one like the "120mm" (you know the 90mm some what resembles the MP-40 and the Zakus MG a Lewis gun) as such is still going to be a lower powered round comparatively (I believe that even the rounds seem to be longer with the 120 than the 90)... Though their are a few things to get around this issue...

Though this dose leave a question what kind of ammo dose gundam use? From what I recall most of the images I have seen seem to indicate a full caliber round much like WW2 era ammo, and not rounds like APFSDS (which do seem to exist with tank ammo as Igloo 2 indicates, but Mobile suits do not seem to use them). Though rounds like APCR and HEAT are much lighter than APCBC/HE rounds... But I do not think theirs much info to really say.

Edit, it also seems that in another thread you indicate that the Zaku MG has a rate of fire of only 280 rpm? Which is interesting.

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Re: MS handgun caliber

Post by toysdream » Fri Sep 27, 2013 2:56 am

The Lewis gun is actually a pretty perfect human-scale analogue for the Zaku machine gun. In fact, the Perfect Grade version of the Zaku machine gun magazine looks almost exactly like the pan magazines of the Lewis gun and the Soviet Degtyaryov machine gun - both of which hold 47 rounds of 7.62mm ammunition (with a diameter of about 12mm at the base of the case).

Judging from the images I found on Google, it looks like the Lewis and Degtyaryov magazines store the rounds in two layers, with 25 rounds visible on the top layer. Since the PG kit shows 27 rounds inside the Zaku machine gun's magazine, I suppose it might have a capacity of 50 rounds, rather than 47 as per its human-scale counterparts.

Of course, both these weapons are proportionally bigger than the Zaku's weapon - they each measure about 1.25m long (versus 10m for the Zaku machine gun) and weigh about 10kg. Basically, a 7.62mm machine gun is nothing to sneeze at, and if the Zaku machine gun is 10 times this caliber then it would still be pretty fearsome!

Speaking of which, it might be interesting to compare that to the 75mm gatling gun used by the Gouf Custom. Is it possible that both weapons are actually firing the same type of bullet with different casings?

-- Mark

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Re: MS handgun caliber

Post by Nebfer » Fri Sep 27, 2013 5:56 pm

toysdream wrote:The Lewis gun is actually a pretty perfect human-scale analogue for the Zaku machine gun. In fact, the Perfect Grade version of the Zaku machine gun magazine looks almost exactly like the pan magazines of the Lewis gun and the Soviet Degtyaryov machine gun - both of which hold 47 rounds of 7.62mm ammunition (with a diameter of about 12mm at the base of the case).

Judging from the images I found on Google, it looks like the Lewis and Degtyaryov magazines store the rounds in two layers, with 25 rounds visible on the top layer. Since the PG kit shows 27 rounds inside the Zaku machine gun's magazine, I suppose it might have a capacity of 50 rounds, rather than 47 as per its human-scale counterparts.

Of course, both these weapons are proportionally bigger than the Zaku's weapon - they each measure about 1.25m long (versus 10m for the Zaku machine gun) and weigh about 10kg. Basically, a 7.62mm machine gun is nothing to sneeze at, and if the Zaku machine gun is 10 times this caliber then it would still be pretty fearsome!

Speaking of which, it might be interesting to compare that to the 75mm gatling gun used by the Gouf Custom. Is it possible that both weapons are actually firing the same type of bullet with different casings?

-- Mark
It's not unusual for guns of the same caliber be firing the same projectiles but using different cartridges. By the way do we have any real info on the Goufs 75mm gat?

Assuming that the pan mag can hold 27ish rounds per level then to get 100 rounds it needs to be quad stacked which would need the mag to be roughly a half meter tall which in 1/144 scale should be 4mm but my 1/144 Zaku MGs only have pan mags that is 3mm tall, so one can only do 3 levels... Interestingly on the other thread on this topic the linked Chinese forums I believe mentioned that the Pan mag could be 70 to 100 rounds... Though the width of the 1/144 mag is around 15mm which is roughly 2.2 meters (the rounds are what 600ish mm long?), so in theory it should be able to hold ~50ish rounds in a single row, so 100 rounds on two levels should be doable.

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Re: MS handgun caliber

Post by toysdream » Fri Sep 27, 2013 7:02 pm

That doesn't work with the real-world comparison, though. Both the machine guns I mentioned also support double-height 97-round pan magazines, which are really thick; the Zaku machine gun magazine is clearly patterned after the 47-round versions.

The main reason people say the Zaku machine gun has 100 rounds is because of Gundam Century, and that's actually on the low end of the published claims. But all the other machine guns featured in Gundam 0083 have much smaller magazine capacities, roughly equivalent to human-scale weapons, so the Zaku machine gun is really an outlier.

I don't recall seeing any specs on the Gouf Custom's gatling gun, but according to the MG kit manuals, the roughly similar gatling gun carried by the Gundam G05 carries 3,000 caseless 90mm rounds and has a rate of fire of 50 rounds/sec (normally limited to 5-second bursts). That's about ten times the rate of fire of the Zaku machine gun, incidentally.

The Gouf Custom's gatling gun is smaller than that of the Gundam G05, but has a bigger ammo drum - at least, judging from the MG kits. Assuming this ammo drum is laid out like that of the real-world GAU-8 (which seems to be the obvious inspiration), it's essentially a whole bunch of pan magazines stacked on top of each other, with the ammo spiraling through the length of the drum. And indeed, the Gouf Custom's ammo drum has roughly the same diameter as the Zaku machine gun magazine, so it could easily be packed with similar ammunition.

Judging from the MG kit, the Gouf Custom's ammo drum is about 2m in diameter and 3.5m long, which is about twice as wide and twice as long as the GAU-8's ammo drum. The latter holds about 1,200 rounds of 30mm ammunition, so you'd expect that the Gouf Custom would carry less than that. If the rounds are 2.5 times wider, then you'd expect that you could fit 80% as many around the rim of the double-sized drum, and stack 80% as many along the length of the drum - so basic math would suggest it carries about 64% as many rounds total, i.e. about 800 rounds.

Since the Gundam G05's weapon fires bigger bullets and has a smaller ammo drum, the MG kit manual specs are clearly an overestimate! :-)

-- Mark

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Re: MS handgun caliber

Post by Gelgoog Jager » Fri Sep 27, 2013 8:06 pm

I have heard some people say that the newer HGUC, such as the Sazabi, are better proportioned than their older MG counterparts. Given that situation, maybe it would be better to use the newer HGUC kit for a better comparison:

http://dalong.net/review/hg/h117/h117_i.htm

As an extra note, the gatling gun of the Dra-C from the third Unicorn OVA is included as a handheld weapon for the HGUC Dra-C, and the manual of the later even shows that the same weapon can be used by other MS, such as the Zaku F2. While not identical, this weapon do looks quite similar to the Gouf Custom's shield mounted gatling gun:

http://www.gundam-unicorn.net/en/ms/03.html#11
http://dalong.net/review/hg/h133/h133_i.htm

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Re: MS handgun caliber

Post by toysdream » Fri Sep 27, 2013 9:45 pm

The Dra-C gatling gun's a little weird, since it doesn't seem to have any ammo storage at all. Go figure!

As for the Gouf Custom, I don't have the HG-UC of that. (And anyway, it's harder to get accurate measurements from the smaller kits.) But judging from the model sheet art, it seems like the MG kit is properly proportioned in every respect except for the ammo drum diameter being a bit lower than it should be. So in fact, it looks like the Gouf Custom's ammo drum should be exactly the same diameter as the Zaku machine gun's pan magazine, which really does support the idea that they both use the same ammunition.

-- Mark

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Re: MS handgun caliber

Post by Nebfer » Sat Sep 28, 2013 2:16 am

toysdream wrote:That doesn't work with the real-world comparison, though. Both the machine guns I mentioned also support double-height 97-round pan magazines, which are really thick; the Zaku machine gun magazine is clearly patterned after the 47-round versions.
Well that is true though the DP-28s Tank version only had a 60 round drum, which was a bit smaller but taller. Though the Vickers K gun had a 100 round drum mag, but it is tall. Though I did mention that at the lest the 100 round mags should have 4 stacks making it at lest half a meter tall, which is not indicated by at lest the models I have... And seeing a pic of the ammo placed in a DP-28 it only holds a single row. From what I can find the DP-28s mag is roughly 250-270mm in diameter (note early models held 49 rounds, later ones 47) at 255mm in diameter is ~800mm in circumference with each round taking roughly say 17mm rim to rim (leaving a bit of room between each round) which would be 47 rounds. Considering that the Zakus mag is what 2ish meters wide it's circumference is around 6.5 meters dividing that by 130mm, is some 50 rounds. The Lewis guns mag looking at it's ammo lay out is very open in comparison (roughly 10mm between cartridges, the DP is only like 2mm), you could probably stick roughly 60% more rounds in their if they put them in like the DP-28 mag did. The over all diameter of the mag is ~8.5 inches.
Lewis gun mag -scroll down to find image.
The main reason people say the Zaku machine gun has 100 rounds is because of Gundam Century, and that's actually on the low end of the published claims. But all the other machine guns featured in Gundam 0083 have much smaller magazine capacities, roughly equivalent to human-scale weapons, so the Zaku machine gun is really an outlier.
Let me guess hundreds? Though that is true the Zaku MG is the only one to have more than 30ish rounds. With it's 280 RPM (that's from that arms catalog thingy right?) that's some 21 seconds worth of ammo, quite the endurance advantage their.
I don't recall seeing any specs on the Gouf Custom's gatling gun, but according to the MG kit manuals, the roughly similar gatling gun carried by the Gundam G05 carries 3,000 caseless 90mm rounds and has a rate of fire of 50 rounds/sec (normally limited to 5-second bursts). That's about ten times the rate of fire of the Zaku machine gun, incidentally.

The Gouf Custom's gatling gun is smaller than that of the Gundam G05, but has a bigger ammo drum - at least, judging from the MG kits. Assuming this ammo drum is laid out like that of the real-world GAU-8 (which seems to be the obvious inspiration), it's essentially a whole bunch of pan magazines stacked on top of each other, with the ammo spiraling through the length of the drum. And indeed, the Gouf Custom's ammo drum has roughly the same diameter as the Zaku machine gun magazine, so it could easily be packed with similar ammunition.

Judging from the MG kit, the Gouf Custom's ammo drum is about 2m in diameter and 3.5m long, which is about twice as wide and twice as long as the GAU-8's ammo drum. The latter holds about 1,200 rounds of 30mm ammunition, so you'd expect that the Gouf Custom would carry less than that. If the rounds are 2.5 times wider, then you'd expect that you could fit 80% as many around the rim of the double-sized drum, and stack 80% as many along the length of the drum - so basic math would suggest it carries about 64% as many rounds total, i.e. about 800 rounds.

Since the Gundam G05's weapon fires bigger bullets and has a smaller ammo drum, the MG kit manual specs are clearly an overestimate! :-)

-- Mark
800 to 1,000 or so rounds should be fairly reasonable, though if you pack it in their you might be able to stuff 1200 rounds, though that might be pushing it a bit.

Hold on
If the Goufs Ammo drum is 2 meters in diameter and 3.5 meters long (with a 0.6 meter hollow core where the ammo is wrapped around) than it has roughly 10 cubic meters of volume, each round of ammo at 12cm in diameter and 700mm long takes up only .008 cubic meters of volume so you could stuff it with ~1250 rounds.

Now the Ammo drum on the GAU-8 on the A-10 is 88cm wide by 1.82m long and can hold up to 1,350 rounds (but typically only holds 1,174 or 1,150 rounds) volume wise If I got it right that's about 1 cubic meter of space. A single round of 30x173mm (~30cm long) ammo is about .00048 cubic meters, so by volume it can hold about 2,080 rounds of ammo. So about 1/3rd of it's volume is taken up by the feed system (the wasted space at the center was factored in earlier). So with the Goufs drum having a max of 1250 rounds multiplied by .66 is what due you know 825 rounds.

You know I wonder if theirs any 75mm cartridges that have a case diameter of 120mm... Goes looking, opens up German WW2 era Cartridge case schematics... Indeed their are The 7.5cm KwK 42 (Panthers gun) cartridge case Drawing number 6387 is 123mm in diameter at the rim and is 632mm long it's also 3.3kg in weight. So a 75mm gun with a cartridge case being 120mm has historical precedent.
The 7.5cm KwK 40 (Panzer IV L48) has a 111mm wide case and is 495mm long, by the way.

Any dimensions of the Zakus cartridges (likely gonna have to dig)?

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Re: MS handgun caliber

Post by toysdream » Sat Sep 28, 2013 3:36 pm

Pure volume isn't the limiting factor, though. When you look at how the rounds are stored inside a pan magazine or GAU-8 ammo drum, you'll see that the inward-facing rounds come closest to touching at the point where the casing ends, leaving a fair amount of space between each round at the outer edge. (Dear readers: If that sounded confusing, see Wikipedia's sample image of a pan magazine, which should clear things up.)

So once we allow for the thickness of the magazine itself, and set things up so that the rounds are almost-but-not-quite touching at the "shoulder" of the casing, we've lost quite a lot of the theoretical volume for purely practical reasons. We could try to math and measure all this out, but I think it's simplest to just take the Lewis gun specs and scale them up. And since there's an optional 97-round magazine for the Lewis gun, we can even say that the 100-round capacity associated with the Zaku machine gun refers to an optional large-size magazine that's never actually used in the animation. :-)

As far as the Zaku machine gun's rounds, the PG kit indicates they're about 60cm long, which is the same length as the ammo slot in most depictions of the gun itself (such as Katoki's model sheet art for the MMP-78). This is proportionally really short - the rounds fired by the human-scale Lewis gun are 80-85mm long overall, and the rounds fired by the 7.5cm KwK 42 you mentioned are about 90cm long overall. (With a total weight per round of 11-14kg, depending on type of ammunition.) So even if the Zaku machine gun's rounds are dainty 75mm bullets swaddled in a crunchy 120mm casing, they're still proportionally pretty stubby compared to human rifles or tank cannons. But it's not hard to hand-wave that away and say they're actually longer, and people just keep making the ammo feed slot too small...

One place where I've seen (unofficial) diagrams of the Zaku machine gun's rounds is in the second volume of Another Century Chronicle. Here, the overall round is about 4.8 times longer than the base diameter, and the base diameter is 1.5 times that of the actual bullet. So this is actually compatible with a base diameter of 120mm, overall length of 600mm, and bullet diameter of 80mm. The Zaku I's 105mm round, shown alongside it, is proportionally smaller in both casing and bullet diameter.


EDIT: Ah, and here's another data point. According to the MSV-R handbook series, the 120mm gatling gun attached to the back of the MS-07G-2 Gouf Tactical Assault Type is hooked up to a cylindrical magazine with a capacity of 300 rounds. Measuring from the rear view of the Gouf, it looks like the gatling gun itself is about 8 meters long from muzzle to swivel joint, and less than a meter in diameter (a little smaller than the Gouf Custom's weapon). It's connected to a cylindrical magazine measuring about 2 meters across and 3.3 meters high (again, similar to the Gouf Custom). The chain connecting the gun to the magazine is only about 500mm wide - pretty short for a 120mm round!

The diagrams in the back of the book show the casing ejection slot (which isn't visible in the regular line art) and a sample round, which seems to be roughly 600mm long and less than 100mm in diameter. Honestly, this seems even punier than the regular Zaku machine gun ammo, and it certainly looks more petite than the 120mm gatling gun used by the Zaku Cannon. But if we're inclined to be generous, I could see this being the same ammo used by the Zaku machine gun - a round 120mm in diameter and 600mm in overall length, with the actual bullet diameter about 75-80mm. On the whole, its dimensions are so similar to the Gouf Custom's gatling gun that I think we can probably think of them as the same weapon.

-- Mark

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Re: MS handgun caliber

Post by Nebfer » Sun Sep 29, 2013 12:06 am

toysdream wrote:Pure volume isn't the limiting factor, though. When you look at how the rounds are stored inside a pan magazine or GAU-8 ammo drum, you'll see that the inward-facing rounds come closest to touching at the point where the casing ends, leaving a fair amount of space between each round at the outer edge. (Dear readers: If that sounded confusing, see Wikipedia's sample image of a pan magazine, which should clear things up.)

So once we allow for the thickness of the magazine itself, and set things up so that the rounds are almost-but-not-quite touching at the "shoulder" of the casing, we've lost quite a lot of the theoretical volume for purely practical reasons. We could try to math and measure all this out, but I think it's simplest to just take the Lewis gun specs and scale them up. And since there's an optional 97-round magazine for the Lewis gun, we can even say that the 100-round capacity associated with the Zaku machine gun refers to an optional large-size magazine that's never actually used in the animation. :-)
Seems you practically ignored how tightly spaced the DP-28s ammo is compared to the Lewis, and even they are not touching, the examples I gave the ammo would not be touching (The DP-28 example has the rounds at 5mm apart from their rims, which is a bit more than what the pic I provided indicates). With the volume based calculations I cut it by 1/3rd over the over all capacity, partly to account for the ammo not to be touching each other. Which is why I did a examination of the GAU-8s mag, as we know how big it is, and how many it can hold, volume wise it should hold nearly 2100 but in real life holds only at max 1,350 (and often only 1,150).

Lets try the Lewis's pan magazine (with 47 rounds) it is ~210mm wide and ~28mm tall (with a ~40mm dead space in the middle), giving a volume of roughly 930 cubic centimeters a single round of .303 British has a volume of 12 cubic centimeters (at 14mm wide and 78mm tall), as such the magazine should hold 77ish rounds well lets see 2/3rds of 77 happens to be 51 rounds... Humm looks like again only using about 2/3rds (+ or - a few percent) of the max from what the volume suggests works out fairly well (an error of only 8.5%).

As such volume wise if the Zakus mag is 2.1m wide, 0.4m tall with a 0.9m dead space at the center, it would have roughly 1.1 cubic meters of space, which would hold 160 rounds of ammo (if the max case diameter is 120mm), cut by 1/3rd to account for ammo not touching each other, and other bits, you get 106, so yes it's perfectly plausible for their to be 100 rounds in their, assuming the cartridge cases are 120mm in diameter and not the projectiles (that would make a case for 50ish rounds -which would work with the 24ish "raised panels" along the out side of the Mag which resembles the ones on the Lewis guns magazine, which is where the cartridges rims are placed)...
As far as the Zaku machine gun's rounds, the PG kit indicates they're about 60cm long, which is the same length as the ammo slot in most depictions of the gun itself (such as Katoki's model sheet art for the MMP-78). This is proportionally really short - the rounds fired by the human-scale Lewis gun are 80-85mm long overall, and the rounds fired by the 7.5cm KwK 42 you mentioned are about 90cm long overall. (With a total weight per round of 11-14kg, depending on type of ammunition.) So even if the Zaku machine gun's rounds are dainty 75mm bullets swaddled in a crunchy 120mm casing, they're still proportionally pretty stubby compared to human rifles or tank cannons. But it's not hard to hand-wave that away and say they're actually longer, and people just keep making the ammo feed slot too small...

One place where I've seen (unofficial) diagrams of the Zaku machine gun's rounds is in the second volume of Another Century Chronicle. Here, the overall round is about 4.8 times longer than the base diameter, and the base diameter is 1.5 times that of the actual bullet. So this is actually compatible with a base diameter of 120mm, overall length of 600mm, and bullet diameter of 80mm. The Zaku I's 105mm round, shown alongside it, is proportionally smaller in both casing and bullet diameter.

-- Mark
Effectively smiler to the 7.92x33 Kurz (StG 44) and 7.62x39 (AK-47).
Any info on the gun and or ammo, like types, HEAT, APC, APDS, HE and ect?

Over all in short if the round is 75ish mm in diameter with a cartridge case being 120mm, than it's not impossible for the Zakus Pan Mag to hold as many as 100 rounds, if the round diameter is 120mm with a as you indicated case that's 1.5x wider (i.e. 180mm) then max you could feasibly put in their is around 50 (the calculation Ironically indicates 47).

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Re: MS handgun caliber

Post by toysdream » Sun Sep 29, 2013 3:13 am

I do think the Lewis gun magazine seems like a pretty perfect analogue to a Zaku machine gun magazine, assuming the rounds themselves (rather than the bullets inside) are 120mm. The Zaku magazine is about ten times the diameter, the rounds are ten times as big, and the available cutaways indicate that there are about as many per layer within the magazine - I count 25 per layer for the Lewis gun, versus 27 per layer for the Perfect Grade Zaku II and 26 per layer for the Master Grade Zaku II ver. 2.0.

In that case, it's really just a question of how many layers the Zaku machine gun has. Although the thickness of the magazine varies from one depiction to another, in practice it seems to fall in between the 47-round and 97-round Lewis gun magazines (which are about 28 and 56mm high, respectively). Most interpretations of the Zaku machine gun magazine seem to be 40-50cm high, which is about what you'd expect for three layers.

Meanwhile, it looks like the Degtyaryov (DP-28) manages to pack all 47 rounds into a single layer, versus the two layers of the Lewis gun (or four layers for the 97-round magazine). No wonder they're packed in so tightly! The magazine itself is also quite a bit wider - about 27cm in diameter, 30% more than the Lewis gun or a human-scale Zaku machine gun. In theory, I guess you could have a double-layered Degtyaryov-style pan magazine with a hundred rounds, but it would probably need to be a lot wider and the model kits that show the interior of the Zaku machine gun version make it look like the Lewis gun instead.

In the end, then, it seems like a matter of personal preference. If you really want to go crazy, you could treat the Zaku machine gun magazine like a double-layered Degtyaryov with 100 rounds; if you want to be ultra-conservative, you could treat it like a scaled-up Lewis gun with 50 rounds, and attribute the magazine's extra thickness to heavier armor; and if you want something in between, you could probably consider a three-layered Lewis gun type, with 75-80 rounds.

But one way or another, I think it's hard to justify going higher than 100 rounds per magazine, and the comparison to these real-world machine guns makes it really quite obvious that bullets themselves can't possibly be 120mm in diameter! :-)


As for ammo types, Another Century Chronicle lists four types - "normal", armor-piercing, fin-stabilized armor-piercing, and scattershot.

The Gundam Museum catalog - which I'd consider a bit more "official" because it was Sunrise-supervised - lists the Ap-3 armor-piercing, St-4 anti-ship armor-piercing, and Ht-3 shaped-charge explosive types. The Ap-3 is an APC (Armor-Piercing Capped) round based on an existing shell used by armored vehicles; known as the "Type 73", it was developed alongside the Zaku. The St-4 is an APCR (Armor-Piercing Composite Rigid) round known as the "Type 75", with a lighter weight and higher muzzle velocity, which is intended mainly for space use. The Ht-3, or "Type 79", was designed for use against armored vehicles on the ground and was developed at the last minute for the Earth invasion.

-- Mark

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Re: MS handgun caliber

Post by Gelgoog Jager » Sun Sep 29, 2013 3:44 pm

What types of ammo can be loaded into the small catridge that can be alternatively used on the MMP-78? Said catridge can be seen in the lineart of the MMP-78, included in the profile of the MS-06F2. In 0083 it seems to have been used to carry AA rounds or something similar to shoot down the GP01's stolen Core Fighter. Also, can it still be loaded with regular 120mm rounds?

By the way, that small catridge reminded me of the obscure rifles from the PS2 game, Zeonic Front, which also came in the two known different calibers: 120mm and 90mm. Is there any official ifno about these weapons?

Finally, while the MMP-78 and MMP-80 seem to be the definitive versions of the Zaku machine guns, the later seen MMP-80 ver.8 seems to be the more widely available model. Is it right to assume that this version was a late simplified model, maybe even developed by Zeon remnants?

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Re: MS handgun caliber

Post by toysdream » Mon Sep 30, 2013 4:15 am

First, one more data point on the classic Zaku machine gun...

I just remembered that the original machine gun has a casing ejection slot, so I figured we could try measuring from that. As it turns out, the original model sheet from First Gundam also had a side view schematic, which is even more useful:

http://www.ultimatemark.com/gundam/imag ... inegun.jpg

I'm using Comic Bombom's length spec of 10.83m here, as recently mentioned in the Zeon Handheld Weapons thread. This is a bit larger than most of the model kit renditions, but the Perfect Grade Zaku II's rifle is scaled to 11 meters, so it seems plausible enough.

First thing you'll notice is that the side view schematic indicates the magazine has a diameter of about 266cm, which is exactly ten times that of the aforementioned Degtyaryov machine gun. In this case, it actually is possible to cram 50 rounds each into two layers, for the oft-cited 100 rounds! The casing ejection slot, meanwhile, is about 55cm long - enough for a decently-proportioned rifle round. (As you'll recall, most other examples suggested that the entire round is 60cm long, not just the casing, which is a bit stubby for rifle ammunition.)

The other views suggest a slightly smaller magazine - about 240-250 cm in diameter. Even so, if you compare them to the model kits, you'll see that later depictions of the rifle all have a proportionally smaller magazine. The original model sheet gave it a big old pan that conceivably could carry 100 rounds, but later designs have shrunk the magazine to Lewis gun proportions.


As for the small magazine used by the MMP-78, this is used for anti-air rounds. No info on the rifle variants from Zeonic Front, as far as I know. And the "Ver.8" designation is just used in the Master Grade Zaku II kit manual to refer to the generic MMP-80 - there's apparently nothing remarkable about this version.

-- Mark

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Re: MS handgun caliber

Post by Nebfer » Tue Oct 01, 2013 3:48 am

toysdream wrote:I do think the Lewis gun magazine seems like a pretty perfect analogue to a Zaku machine gun magazine, assuming the rounds themselves (rather than the bullets inside) are 120mm. The Zaku magazine is about ten times the diameter, the rounds are ten times as big, and the available cutaways indicate that there are about as many per layer within the magazine - I count 25 per layer for the Lewis gun, versus 27 per layer for the Perfect Grade Zaku II and 26 per layer for the Master Grade Zaku II ver. 2.0.

In that case, it's really just a question of how many layers the Zaku machine gun has. Although the thickness of the magazine varies from one depiction to another, in practice it seems to fall in between the 47-round and 97-round Lewis gun magazines (which are about 28 and 56mm high, respectively). Most interpretations of the Zaku machine gun magazine seem to be 40-50cm high, which is about what you'd expect for three layers.

Meanwhile, it looks like the Degtyaryov (DP-28) manages to pack all 47 rounds into a single layer, versus the two layers of the Lewis gun (or four layers for the 97-round magazine). No wonder they're packed in so tightly! The magazine itself is also quite a bit wider - about 27cm in diameter, 30% more than the Lewis gun or a human-scale Zaku machine gun. In theory, I guess you could have a double-layered Degtyaryov-style pan magazine with a hundred rounds, but it would probably need to be a lot wider and the model kits that show the interior of the Zaku machine gun version make it look like the Lewis gun instead.

In the end, then, it seems like a matter of personal preference. If you really want to go crazy, you could treat the Zaku machine gun magazine like a double-layered Degtyaryov with 100 rounds; if you want to be ultra-conservative, you could treat it like a scaled-up Lewis gun with 50 rounds, and attribute the magazine's extra thickness to heavier armor; and if you want something in between, you could probably consider a three-layered Lewis gun type, with 75-80 rounds.

But one way or another, I think it's hard to justify going higher than 100 rounds per magazine, and the comparison to these real-world machine guns makes it really quite obvious that bullets themselves can't possibly be 120mm in diameter! :-)
It all depends on how large the individual rounds are, you can fit a lot more smaller rounds than bigger rounds in the same volume. Though it also depends a bit on how you store them, dense like the DP-28 or a bit more loose like the Lewis.
As for ammo types, Another Century Chronicle lists four types - "normal", armor-piercing, fin-stabilized armor-piercing, and scattershot.

The Gundam Museum catalog - which I'd consider a bit more "official" because it was Sunrise-supervised - lists the Ap-3 armor-piercing, St-4 anti-ship armor-piercing, and Ht-3 shaped-charge explosive types. The Ap-3 is an APC (Armor-Piercing Capped) round based on an existing shell used by armored vehicles; known as the "Type 73", it was developed alongside the Zaku. The St-4 is an APCR (Armor-Piercing Composite Rigid) round known as the "Type 75", with a lighter weight and higher muzzle velocity, which is intended mainly for space use. The Ht-3, or "Type 79", was designed for use against armored vehicles on the ground and was developed at the last minute for the Earth invasion.

-- Mark
Interesting APCR would be some what logical in space, a bit odd but logical in a way. Though it's a bit odd for them to be using APC in ground combat.

I do not know how much you know about Armor penetrator design but here's a quick run down of the history (to be fair im hardly an expert my self).
To penetrate armor you need effectively two things, Speed and Length (theirs likely more to it but As far as I know...), both have some issues, to get traditional AP rounds to go really fast required stupidly long barrels and lots of propellant (you could also use hotter propellents but that has it's own issues as well, namely barrel erosion). Alternatively you could make the rounds longer but that increases weight and runs into a big issue, stability, a traditional spin stabilized round has a maximum length of around 5 or 6 times it's own length, longer than that and the round would be in adequately stabilized and thus inaccurate. This is why if you looked at the length of most rounds their around 3 to 4 times their own width. Well Early on old fashioned AP rounds where good enough for the job, but as armor got thicker (most evident in the naval side of things) velocity needed to be increased to match. At first longer barrels and increased propellant loads where enough to do the job but as barrels increased their size became problematic (particularly on land). Increasing velocity's resulted in a issue with regular AP rounds, steel simply started to shatter (known as shatter gap), to help this a cap was used to lessen the shock Hence APC. However the best shapes for this cap was often not the most aerodynamic so an aerodynamic nose was placed over the this cap, this is where APCBC comes from (also all three types can come with a variant where a small HE charge is placed to cause further damage after penetration, this cost a small amount in the armor penetrative effect but it was often felt worth the loss, as such these often are noted with the /HE suffix (most German rounds are of this type)).

These speed issues resulted in APCR a projectile with an outer layer of steel or aluminum (often called a shoe or sabot) built around a hard and dense core, often made from tungsten-carbide or just tungsten (APCR is a British term, Hartkern (Hard Core) is the German name*, and the US term is HVAP). This round resulted in a much lighter round in roughly the same size package as the older AP rounds. the higher speed resulted in a noticeable increase in Armor penetration. But it had a noticeable problem, due to it's construction the sectional density was off as a result the round slowed down a lot faster than more traditional rounds, at longer ranges it's advantages where minimal. By the End of WW2 the solution to this was found in the name of APDS, similar to APCR it featured a small core of dense metal built around a light weight shoe/sabot, unlike APCR this sabot was discarded shortly after it left the barrel, this removed the sectional density issues and allowed APDS to be useful at much longer ranges. However during and after WW2 Tank armor increased further and even APDS found it self hard to keep up as it was still spin stabilized which had that length issue. This is why you see some interest in HEAT rounds after the war over APDS. To over come this engineers turned to lengthening the sub caliber core of the APDS round, which resulted in largely abandoning spin stabilization and the use of fins to do this, resulting in APFSDS.

Though why it makes some sort of sense, is that APCR would increase velocity (thus effective range and damage) but dose not have the issue of having to discard sabots (debris) and you would have to get the sabots to discard in space (likely via centripetal force), and Fins would be useless.

* the Germans also some times used Wolframkern, Wolfram is German for tungsten (which is also why Tungsten has the Elemental symbol of W).
toysdream wrote:First, one more data point on the classic Zaku machine gun...

I just remembered that the original machine gun has a casing ejection slot, so I figured we could try measuring from that. As it turns out, the original model sheet from First Gundam also had a side view schematic, which is even more useful:

http://www.ultimatemark.com/gundam/imag ... inegun.jpg

I'm using Comic Bombom's length spec of 10.83m here, as recently mentioned in the Zeon Handheld Weapons thread. This is a bit larger than most of the model kit renditions, but the Perfect Grade Zaku II's rifle is scaled to 11 meters, so it seems plausible enough.

First thing you'll notice is that the side view schematic indicates the magazine has a diameter of about 266cm, which is exactly ten times that of the aforementioned Degtyaryov machine gun. In this case, it actually is possible to cram 50 rounds each into two layers, for the oft-cited 100 rounds! The casing ejection slot, meanwhile, is about 55cm long - enough for a decently-proportioned rifle round. (As you'll recall, most other examples suggested that the entire round is 60cm long, not just the casing, which is a bit stubby for rifle ammunition.)
Question if 550mm long rounds are "decently proportioned" why are 600mm rounds not so? Unless you think only cases have to drop out of their... What happens if a round misfires? Where dose it go? Though a case length of 550mm would be proper full sized rifle cases (scaled up 10x).

An over all length of ~550mm would result in a round looking a bit like the Russian 7.62x39 round which is 56mm long.
Though their is this one which is 60mm long and of you want a more German flavor theirs nothing wrong with Kurz at ~49mm in length, at 500mm in length a 490mm long cartridge would have some room to be ejected and not hit the sides. Though theirs one small problem here a 10x upscale would mean the rounds are only firing ~80mm projectiles not 120mm, to do that from real life small arms requires a 16x upscale making these rounds way to long ranging from 780 to 960mm in over all lengths, to say noting of full length rifle ammo (~1.2m).

To be properly scaled to fit in a ~550mm long ejection port a 120mm round would have to some what resemble a 7.62x25 Tokarev Pistol cartridge, this being a 16x scale increase for the Tokarev (the 7.63x25 Mauser is a very smiler round (it's the parent of the Tokarev in fact)), 16x the size either round results in a projectile diameter of 122mm (rounding off to the nearest whole cm/mm is not unheard of) and an over all length of 540 to 560mm (cartridge case being 400mm long by ~160mm wide).

Though this assumes you need a ejection port roughly as long as the rounds over all length to safely eject it... (if you don't then you probably could get away with a round roughly the size of the 7.92 Kurz).

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Re: MS handgun caliber

Post by toysdream » Tue Oct 01, 2013 4:08 am

Yeah, a 550-600mm ejection slot would be reasonable if it only needs to fit the casing (rather than the entire round). In that case, you could actually have rifle-style rounds in there. If it needs to fit the entire round, then I guess that supports the depiction in the PG kit, where the entire round is about 600mm, which is a little stubby but not too bad.

In any case, I think the one thing we've established is that the bullet diameter can't possibly be 120mm - this pretty much HAS to be the diameter of the entire round.

Now, what can we say about those so-called 60mm vulcans, hm?

-- Mark

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Re: MS handgun caliber

Post by Ferrus_Manus » Tue Oct 01, 2013 1:16 pm

toysdream wrote:Yeah, a 550-600mm ejection slot would be reasonable if it only needs to fit the casing (rather than the entire round). In that case, you could actually have rifle-style rounds in there. If it needs to fit the entire round, then I guess that supports the depiction in the PG kit, where the entire round is about 600mm, which is a little stubby but not too bad.

In any case, I think the one thing we've established is that the bullet diameter can't possibly be 120mm - this pretty much HAS to be the diameter of the entire round.

Now, what can we say about those so-called 60mm vulcans, hm?

-- Mark
The 20x102mm ammo used by the classic M61 Vulcan has a base diameter of ~29mm, and the 30mmx173 of the GAU-8 Avenger has a base diameter of around 45mm. I guess the 60mm Vulcan has a bullet diameter in the neighbourhood of 40 to 50mm.
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Re: MS handgun caliber

Post by toysdream » Tue Oct 01, 2013 2:06 pm

I wouldn't automatically assume that the listed caliber = round diameter for all U.C. weapons. It's really a question of figuring out what's physically plausible and then working backwards from there.

The MMP-80 Zaku machine gun, for example, seems pretty plausible with 90mm bullets. Then again, judging from the model sheet, the round and bullet diameter are basically identical for this weapon anyway - it doesn't have the rifle-style narrowing associated with the standard Zaku machine gun. (In other words, it basically uses pistol ammunition, just like a real-world submachine gun.)

So what's plausible for those head vulcans? How would we begin figuring that out?


Perhaps we can start with the Alex's forearm gatling guns. Supposedly these are 90mm weapons; they're stored inside the Alex's arm covers, with extendable barrels that slide out when in use, and the ammo is stored in a big drum inside the forearm itself. In the last episode of Gundam 0080, Chris notes that the Alex only has 500 rounds left in its right arm, and from the onscreen display it looks like the weapon is at about 2/3 capacity. So full capacity is probably about 800 rounds per arm.

Since we've just been doing all this number-crunching on gatling gun drum magazines, it should be possible to estimate the maximum possible size of the Alex's magazine and then figure out what size the ammo would need to be to fit 800 rounds in there. That should give us an initial reality check. At first glance, it looks to me as if the 1,200-round magazine of the GAU-8 is actually bigger than the Alex's forearm, but you could probably fit 800 rounds inside the arm if it was using the same 30mm ammo as the GAU-8.

-- Mark

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Re: MS handgun caliber

Post by Gelgoog Jager » Tue Oct 01, 2013 6:22 pm

Speaking of vulcans, as you might recall MSV-R added a MS-06F Shin Matsunaga Custom with four 30mm vulcans isntead of the four 40mm vulcans of the unit used by Garma. Would it be possible for these units to actually have the same weapon, just using a different ammo?

Also, take this with a grain of salt, but I seem to recall reading somewhere that one of the reasons for which the MMP-80 became widespread among Zeon remnants after the OYW, was because it could be loaded with EF 90mm rounds. Is there anything that can confirm such scenario?

Maybe in a similar spot, but could the 60mm vulcans of the MS-06D from ZZ also be a modification that took place in order to use EF 60mm ammo?

I can't recall if there is any caliber information for the vulcans of the original MS-06D from MSV, or for the MSM-01 and MS-05L for the matter.

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Re: MS handgun caliber

Post by toysdream » Tue Oct 01, 2013 6:27 pm

Before we get into the replies, here's a scaled comparison of the Alex, its forearm gatling, and the aforementioned GAU-8 gatling gun:

http://www.ultimatemark.com/gundam/imag ... _scale.jpg

As we can see, the Alex's gatling is roughly the same length and overall diameter as the GAU-8, although its barrels are proportionally shorter and thicker. (It also has only three barrels.) The GAU-8's 1200-round magazine is clearly too big to fit inside the Alex's forearm, but it's not hard to imagine an 800-round version fitting in there.

From a practical standpoint, then, the Alex's 90mm forearm gatlings really should be equivalent to the 30mm GAU-8, both in terms of gun size and ammunition storage. That's much smaller than the official spec, but in real-world terms the tank-destroying GAU-8 is a tremendously impressive weapon. And from an ammo standpoint, it's insane to think you could cram the equivalent of 800 rounds of pistol ammunition into each forearm!

If the same proportion holds true for the 110mm machine guns in the forearms of the Gelgoog Marine and Gerbera Tetra, perhaps these would be equivalent to 37mm anti-aircraft guns. And the ubiquitous "60mm vulcan gun" would actually be a 20mm weapon, just like the ones used in real-world aircraft. As we can see, the real-world M61 Vulcan is way too big to fit in a mobile suit's head, but with fewer and shorter barrels it could just about squeeze in there.

Gelgoog Jager wrote:Speaking of vulcans, as you might recall MSV-R added a MS-06F Shin Matsunaga Custom with four 30mm vulcans isntead of the four 40mm vulcans of the unit used by Garma. Would it be possible for these units to actually have the same weapon, just using a different ammo?
I think these are all supposed to be the same weapon, it's just that different sources have disagreed about the actual caliber. Same thing with the Core Fighter's 25/30mm nose vulcans, which might be another useful example to look at.
Also, take this with a grain of salt, but I seem to recall reading somewhere that one of the reasons for which the MMP-80 became widespread among Zeon remnants after the OYW, was because it could be loaded with EF 90mm rounds. Is there anything that can confirm such scenario?
I don't recall hearing that before, but it's something to research.

One other One Year War machine with unusual vulcans would be the Acguy, whose head guns are supposed to be 105mm. Let's mark that down as a future case study along with the Core Fighter.

-- Mark

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