How much obtuation from a 1:20 gg bullet can one hope to achieve? I have 3 rifles that have been known to only perform well with a soft, paper patched bullet, a m71 mauser, .433 peabody and a French gras.

So far I have only been successful woth paper patch bullets with an m71 mauser with a 1:20 alloy, 400g bullet patched to .446 in a .452 groove barrel. I have not tried naked. A similar load with soft lead bullet patched didn't shoot well at all.

The peabody went against all advice and shot extraordinary well with a naked .442 400g bullet in a .454 bore. Oddly enough the grooves look relatively shallow compared to other rifles that require patching.

A French gras that has been giving me fits has a .452 bore and will chamber a .446 bullet MAX.

Why can't we simply use a grease groove bullet instead of a patched bullet since the alloys used are the same hardness? How far can we reasonably expect a 1:20 alloy bullet to bump up?

Steve, my 71 Mauser carbine likes Lyman 446110 hollow point grease grooves in 1 to 20 sized .446 with 4759, or BP in the 80-82 range. No bump up necessary. My trapdoor shoots the 405 grain Lee hollow base grease grooves in 1 to 20 sized .409 in the .460 some odd barrel with BP just fine.