Greg Hennessy wrote in message . ..
On Sat, 27 Dec 2003 19:08:02 +0200, "Jukka O. Kauppinen"
wrote:


What was the timetable for British development for their 20 mm cannon
ammuniation during WW2?


Would Dr Williams please pick up the white courtesy phone.... lol!

No Doctorate - that's Emmanuel!

The RAF started with HE of French design, but found that the fuze
operated too quickly and tended to detonate on the surface of the
target. They solved this by removing the striker from the fuze and
found out that this provided the right amount of delay. This happened
right at the end of 1940 so was in common use in 1941. Around the
middle of 1941, they changed the filling from HE to HEI, which was
found to be more effective.

They also used ball ammo early on (just an empty steel shell - we'd
call it Target Practice now) in lieu of AP - it would punch through
about a half-inch of plate, and sometimes proved more destructive
initially than the fast-fuze HE. They continued to use ball mixed with
HE/HEI in the belts until 1942, when the SAPI came along. This was
just an HE shell filled with incendiary material and with a hard steel
piercing cap instead of a fuze; it could penetrate around 20mm plate.
From then on, the standard belt mix was two HEI followed by two SAPI.

They were interested in an AP for anti-tank purposes and a
tungsten-cored 20mm APCR was developed by Janecek (of Littlejohn
squeezebore fame). Penetration was spectacular (figures range from
45-65mm) but it seems there were ballistic problems and it was never
adopted. The USAAF had a plain steel AP shot, but AFAIK the RAF never
used one.

Tony Williams
Military gun and ammunition website: http://www.quarry.nildram.co.uk
Discussion forum at: http://forums.delphiforums.com/autogun/messages/