uglyrussian308

No problem with either 308 or 7.62 X 51. My Saiga 308, 16.5" actually has a tighter chamber than just about any 308 auto loader I've ever had, (inclusive of FALs and NM M1As). The fired cases from my Saiga will actually chamber in one of my 308 bolt guns with a factory 308 Barrel. The fired brass resizes in an RCBS small base sizer with very little effort. Despit the tight chamber, the brass shws no sign of sticking (ie. no extractor marks on the cartridge rim etc.). I don't know if this is unique to the rifle that I have but it's certainly very impressive. This weapon has exhibited flawl

Don't know if you've drilled it yet but I would go smaller. The closer you move it toward the chamber more important it is to go smaller. You can always open it up later if you find it necessary. I had a converted Saiga .223 several years ago that I actually had to reduce the gas port down in size (via bushing) to reduce the bolt carrier cycling velocity. Cycling was so violent that it would sometimes override the next round in the magazine. - Good luck!