The 311365s that Paul is talking about are cast of a very hard yet malleable, alloy.  Though he's shooting them slower, I've found they're easily good for 2000fps.  Honestly, I think I've had them up around 2300-2400fps using a case full of slow burning powder.  I didn't get a good idea of accuracy at that velocity level, my sights were set for 2000fps and the much faster ones hit over the target.  There was no alloy blowing back on the case neck, a sure indicator of too much pressure for the alloy.  I'll get back to experimenting with them one of these days.  First I need another batch of that alloy!  Rich, this is the copper enriched stuff that you read about on castboolits.  I sorta made the discovery, and badgered ran with it.