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Squeeze-Bore Guns

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Brockpaine

The Shadow

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1

Friday, November 21st 2008, 4:23pm

Squeeze-Bore Guns

Was browsing through some AFV information and ran into an article about the Litlejohn Adaptor. It says that it was an attempt for "squeeze-bore guns" but doesn't give any real information... The closest thing I found was a reference to conical barrels on the sPzB 41 as a "squeeze-bore" theory. Anybody have anything more specific?

Red Admiral

Italian Stallion

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Friday, November 21st 2008, 4:33pm

http://www.quarry.nildram.co.uk/highvel.htm



It really is a squeeze bore. The projectile is a rigid inner (steel or WC) with soft lead as the outer with two flanges around the body that make it fit the barrel. As it travels down the barrel the bore decreases and the flanges get squeezed inwards. The projectile comes out of the barrel with a very high velocity.

APDS has similar results but acts in a different way. The sleeve around the inner penetrator is removed after exiting the barrel by aerodynamic drag.

The problem comes with reduced barrel life and the inability to fire decent HE rounds.

Hrolf Hakonson

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Friday, November 21st 2008, 4:41pm

Squeeze-, taper- or cone-bore guns were historically used by Germany (sPzb41, 42/28mm PaK41, and 75/55mm PaK41) and the UK (Littlejohn adaptors). In WW, Germany uses the Gerhlich design in AT rifles and light AT guns (15/7.92mm and 28/20mm).

Brockpaine

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Friday, November 21st 2008, 5:08pm

Ah, I see.

Are there any existing squeeze-bore guns operational in WW? Is there a need seen yet for them?

Hrolf Hakonson

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Friday, November 21st 2008, 5:14pm

Quoted

Originally posted by Hrolf Hakonson
In WW, Germany uses the Gerhlich design in AT rifles and light AT guns (15/7.92mm and 28/20mm).


There's the answer to your question.... :)

Brockpaine

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Friday, November 21st 2008, 5:18pm

D'oh!

Vukovlad

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Friday, November 21st 2008, 8:59pm

Why is Germany using Gerlich guns? Considering that all tungsten for ammo has to be imported?

thesmilingassassin

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Friday, November 21st 2008, 9:29pm

Not sure why thats a big deal, Austria has it. Shouldn't be too hard to import it from them.

Brockpaine

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Friday, November 21st 2008, 9:35pm

Uh, didn't Germany import Austria, too? :P

Vukovlad

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Friday, November 21st 2008, 9:43pm

Considering all the talk about "experience driven" development why is Germany introducing a expensive and excluding FJ use unnecessary equipment ( they already have state of the art AT guns).

Wasnt aware that Austria had any significant Tungsten mines, the sPzB 41 was withdrawn due to lack of tungsten for ammo OTL, when did the mines open?

This post has been edited 2 times, last edit by "Vukovlad" (Nov 21st 2008, 9:52pm)

thesmilingassassin

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Friday, November 21st 2008, 11:06pm

I can't really say, I'm going by 2005 info, which by the way states that China produces 75% of the worlds Tungsten in 2000. Not sure what those levels would be in 1936/37 but my guess is much lower.

Other producers include Bolivia, Brazil, Portugal (Iberia in WW), Korea (Chosan), Siam and Russia.

Red Admiral

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Friday, November 21st 2008, 11:19pm

Personally I don't feel that squeeze bore guns are worth the effort. You get more penetration for the same weight but a less effective HE shell. For a specialised mission like anti-tank work for paratroopers the lesser weight is more important.

A 37-50mm anti-tank gun is more than sufficient for the moment, no real need to move up to 75mm anti tank guns.

Hrolf Hakonson

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Friday, November 21st 2008, 11:43pm

Why is Germany using them? Because they're an interesting tech item that is lighter than the alternatives and a little (but not too much) different from history. The use of tungsten was a historical problem because Germany was blockaded, right now in WW Germany is not blockaded so the use of tungsten in ammunition (which isn't being used anyway) isn't a problem. In small (37mm or less) AT weapons, the lack of a useful HE round isn't very important, the alternative HE round (the 37mm HE) isn't very useful in most cases.

Vukovlad

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Friday, November 21st 2008, 11:48pm

What kind of penetration are you having with steel AP round? Considering the vehement protests on other 1940 tech I am a bit surprised at the ready acceptance of these guns, true the principle was known much earlier but then again so where the principles behind HEAT and Sterling engines.

Hrolf Hakonson

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15

Saturday, November 22nd 2008, 3:05am

A steel or lead-cored bullet for the 15/7.92mm ATR round should penetrate about like a 7.92mm x 107 Maroszeck, with the tungsten rounds doing around 30-40% better.


The historical steel-cored round for the sPzb41 fired a 139 gram projectile at 1100 m/s, compared to the tungsten-cored round weighing 120 grams at 1400 m/s, The latter is almost 50% more energetic at the muzzle, so it's advantage in penetration is obvious enough. The steel cored round would be about 33% less effective at short ranges, but losing a bit less than that as ranges increase (since it would hold it's velocity a bit better, being heavier).

Kaiser Kirk

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Saturday, November 22nd 2008, 3:32am

Quoted

Originally posted by Vukovlad
What kind of penetration are you having with steel AP round? Considering the vehement protests on other 1940 tech I am a bit surprised at the ready acceptance of these guns, true the principle was known much earlier but then again so where the principles behind HEAT and Sterling engines.


Well, despite the tussels I've gotten into I don't go around *looking* for tech transgressions. Frankly it's not exactly fun to have those conversations, and it's not like it's my task any more than anyone elses. In this case, I remember reading Hrolf's posts as it was developed (which would have still been under the 3-5 period), and didn't seem out of line.

I'm unsure if it's because I know of the paratroop 28mm/20 (now looking that was 1941 for regular production) or because I was thinking the OTL German ATRs were squeeze bore- which isn't quite right, they simply necked down an oversized cartridge for the same effect. Alternately, it may have been one of those months I was busy.

Hood

Ugly Aircraft, Inc

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Saturday, November 22nd 2008, 4:28pm

In WW Britain is not looking at Littlejohn (a great cover name!). Instead the conservative Army types are looking at 6pdr guns. They don't like the new fangled thingy's... :rolleyes: