[John Rogers]

Well at our range in Dulzura CA we have the 1000yard shooters come to practice before their matches at Camp Pendelton and the fellow that used to win most of them before he moved to Utah shot custom made 6mm rifles with custom made cases about the size of 50BMG and very long boat tailed bullets. He would never mention what powder he used or other details, but I was watching his chronograph one afternoon and it read 4110 feet per second +/- 0.0002 between shots and that was why he said he used 3 to 4 custom made barrels a year. His barrels were some sort of weird alloy as was the action(s) that he had made for him and the stocks he made out of carbon fiber in molds he made himself. I guess being one of the developers of the Predator drone system helped him with doing some of the technical things and he was super cautious of everything. As an example, he kept his bullet loads in special boxes that were set in foam to protect them from vibrations when driving. The foam was some that is also used to protect Hellfire Missiles during shipping, not sure how or where he got that from?
Anyways 4000FPS was about as fast as a bullet can travel he said when pushed by gun powder.

I had to do a quick edit due to the question below, the fellow I mentioned makes his own bullets, some sort of solid allow he turns on his lathe at home. I know he only shoots at 300 yards and uses some sort of Kevlar fabric behind the target stand that collects his bullets so he can do measurements after shooting.
John