Thanks for your responses, I think I'll make up a small batch of mixed wheel weights and .22 bullets, cast some .38 158 grain LRN and see what happens.

Where do you guys get your tin to mix with lead? So far, I have only tried straight wheel weight lead which seems to work good for 800 FPS pistol bullets and 1700 FPS rifle bullets with a gas check. I'd like to experiment with some harder bullets.....