In article ,
Peter Kemp peter_n_kempathotmaildotcom@ writes:
On or about 27 Dec 2003 19:04:58 -0800,
(Tony Williams) allegedly uttered:


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, fascinating as always, but I have to ask - APCR? Armour Piercing
mumble mumble?

Armor Piercing Composite Rigid. A dense, hard, penetrating core,
surrounded by a light metal shell to flesh out the shape. It's
generally lighter than a solid shot, so the muzzle velocity is higher.
When it hits, the light sheath is stripped off, and the core, having a
high sectional density, should give more penetration for a particular
velocity. The drawhack is that the lighter shell loses velocity more
quickly than the heavier shot, so that a solid shot is often better
for long range shooting.

Realizing that you didn't really need to have the lightweight sheath
along led to the development of Armor Piercing Discarding Sabot,
(APDS), which drops the sheath (Sabot) on leaving the barrel. The
round then has a better drag/weight ratio, and doesn't lose speed as
quickly.

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster