Significance of 88mm and 105mm ?

[rexford]

Originally posted by demoss:

</font><blockquote>quote:</font><hr /> I've been wondering the same about the 37mm.

1.5 inch.

I've always wondered the same about small arms. Why 7.62mm? Can't it just be 8mm? 5.56mm.. why not 6mm?

.30 cal and .22, respectively. These are basically just redesignated American rounds.</font>

[Dan Robertson]

Originally posted by Stalin's Organ:

Yep - 20pdr Centurions saw action in Korea and Vietnam I think - the later with the Australians.

IIRC the 105 fitted to the Tortoise super heavy assault gun was designated as "32 pdr". Dunno if that's what was developed into the L7 tank gun (the "famous" 105) tho'

The 32pdr was developed from the 3.7inch Anti aircraft gun. This works out as 94mm.

The 20pdr was developed as an anti tank gun designed to equal the 88mm/L71 in power but at a about 5/6 the size. Orginally I think it was to be produced as a towed mount. It would also have been integrated into the Centurian by about 1946 if the war had gone on.

As it was the Centurion developement was froze until 1948, and the 20pdr was just fitted in time to serve in Korea.

By all acounts the Centurion it was very acurate and with APDS very powerfull, (in penetration however it was not very effective in causing enough damage to brew up some abondoned Centurions in that conflict)

The 20pdr was bored out to produce a trials weapon for the 105mm program and it shared recoil systems and a breach block with the 105mm L7 gun.

[Stalin's Organ]

Originally posted by Dan Robertson:

The 32pdr was developed from the 3.7inch Anti aircraft gun. This works out as 94mm.

Ahhh....thanks - I did know that but had completely forgotten!

The 20pdr was bored out to produce a trials weapon for the 105mm program and it shared recoil systems and a breach block with the 105mm L7 gun.

And thanks again - I didn't know that

[Tarquelne]

IIRC:

An Ian Hogg book mentions that Hotchkiss had the St. Petersburg requirement in mind when designing the 37mm gun.

A quick google search turned up the following:

The Hotchkiss round is the daddy of them all in terms of automatic cannon development. Following the Declaration of St Petersburg of 1868, which banned explosive shells weighing less than 400g, it was calculated that 37mm was about the right caliber for a weapon firing shells at least this big.

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

It's not clear to me if Hotchkiss (or someone else) said "One pound is a nice round number close to 400g (damn the metric system!) - lets shoot for a weapon using a 1 lb. shell." or if experimentation with that 400g limit led directly to a 37mm weapon with a round that just happened to weigh about a pound. Were any 37mm (esp. 37mm "autocannon") weapons made prior to the early 1870s?

[Stalin's Organ]

IIRC Nordenfeldt made a multi-barrelled 1 pdr of some sort in the mid-late 1800's for naval use.

Their lever action machinegun was developed in the 1870's, and the 1 pdr was developed from it for anti-torpedo boat use, but I can't find much in the way of good references to it on the net.

[SgtMuhammed]

I don't know if the 88 came about the same way but the reason the U.S. went with the 90 for its AA gun was that that was the size limit for a round that could be easily handled by the gun's crew. Any heavier and rate of fire would have been affected.

[Guest Mike]

Here is a great page on various info relating to small calibre weapons between the wars.