357maximum - thanks for the report, especially on the 35. LR-308 carbine, 1:10, is the only thing I've got that will possibly reach 2500 fps. I'm to ~ 2200 so far but want to try the Cu addition. Sooo, this morning I used copper sulphate to add Cu to the alloy. It worked, I'm not poisoned. Started with 2# of #2, @ 710F, dumped the CuSO4 on top. It turns globby white. Then smush it against the side of the pot till it turns to a grey powder. SnSO4. Removed dross and added 2# 96/4 Pb/Sb and added shot for As. Added more CS, til it wouldn't turn grey anymore. Stir and cook for a while then cast some Lee 401175TL. The mold wasn't clean or up to temp but after 12 or so, I got some good boolits, WD half, AC half. Good base ( I flat based it), drive bands and grooves. Must have some oil in the mould as there are a few bad spots. I'll hammer test to compare with other alloys I have and post results. If good, I'll cast some 308s and report on that. Oh, I used root killer, 25% metallic Cu, ~$6/# 99% from the BB HW store. Oh, forgot to mention, I used ~ 2 teaspoons for the 4# of alloy. The transfer rate between Cu & Sn is 1, I'll recover the Sn from the dross later. I celebrated the success with a big PB & bacon sandwich for lunch.