The UK's Finest Independent Forum for Shooters and Gun Owners. Est 2010.

At least slug your bore and better still take an impact cast of the freebore.

That will tell you which make of 158 gn mould will suit your gun.

Half and half is a good starting point but I suspect 1-3 pewter to lead will be fine.

Thanks for the advice

I just use backstop lead. Most of it is pistol bullets anyway. .22rf lead is good as it contains a small amount of antimony so it can be heat treated pretty hard (research "precipitation hardening"), but you will probably find it will work ok in your application as is. In feeding my .45 M1911 I got down to using virtually pure lead for the bullets, this was before i was criminalised for legally owning such a nasty thing of course.

Tin does not contribute much to hardness by itself but does increase strength without sacrificing to much ductility, which is why it is used for making tankards and gives lead better flow properties, which is why it is used for casting toy soldiers. Modern made tankards haven't been made of true lead / tin pewter for some time, due in part to the forming processes used that don't need the material to have the same ductility. That plus the fear of lead contamination.