Thread: Bullet casting questions

Originally Posted by veitnamcam

The bit i didn't get.

This is from an article by C E Harris might explain better than I can.

"Oversized 30's", like the .303 British, 7.7 Jap, 7.65 Argentine, and 7.62x39 Russian frequently give poor accuracy with .30 caliber cast bullets designed for U.S. barrels having .300 bore and .308 groove dimensions. This is because the part of the bullet ahead of the driving bands receives no guidance from the lands in barrel s of larger bore diameter. The quick rule of thumb to checking proper fit of the forepart is to insert the bullet, nose first, into the muzzle. If it enters clear up to the front driving band without being noticeably engraved, accuracy will seldom be satisfactory."