Hello all, In our never ending search to find affordable 50 BMG projectiles that are not steel cored surplus (fire hazard in So. kalif.), one of our buddies decided to have a bunch of brass turned projectiles made. One of the testers of the new projectile complained of "gas blowby" & the bullet diameter was changed from .510" to .5115". I had no problems w/the original .510" & wasn't too happy to hear that the specs had changed. My 1st question is, has anyone heard of "gas blowby" before. 2nd question, is brass harder than copper? I've fired some surplus ball that had been resized & some of them meassured up to .512". There were never any issues w/rounds being over pressure due to the larger diameter, but since I'm now experimenting w/solid brass, I'm a little concerned about a tight fit in the barrel & possible dangerous pressures that might occur. Any ideas/opinions would be greatly appreciated. Thanks in advance. Chris.