Here is a good one! I dremel'ed the inlet port in the bolt, so that there is not a step anymore. It is now a smooth transition from the back to the front. This should reduce turbulance and increase the flow of air(in theory).
Joker-"How can you shoot women and children?" Heli machinegunner-"Easy...you just don't lead'em so much! HAHAHA! Ain't war hell! HAHAHA" (Full Metal Jacket)