I have a prewar German drilling in 8x57JR and 16 GA. I bought 20 years ago. I ordered a bullet swaging die from Corbin at that time to swage .323 bullets down to .318. I used both Speer and Nosler partition bullets and got excellent accuracy. Killed a 6 point buck in SW Oklahoma with it the second year I owned it. I'm working overseas right now so I don't have access to my loading notes. I believe I was using 4350 or 4831 powder. I was using factory equivalent 8x57 data. Pretty mild, but I don't think it's smart to hot rod prewar drillings.
Seeing as how "northwolf" isn't nitpicking, i'm not either.... But, when it comes to bullets, you "draw" a bullet down, and "swage" a bullet up... So, if you want to make .318" bullets out of .323" bullets, you need a "draw" die...
I have a few draw dies, and they work pretty good, as long as you aren't trying to go down too far...
I agree, drillings and break open guns should "Not" be hot roded... That is, if you want them to last...
DM