as far as a rifle is concerned i have fire lead bullets with normal lube in a 375 winchester up around 1750fps without any signs of leading. Lot of it depending if the diameters and alloy are right.
Back when I had two .375 H&H Magnums in the safe, I cast and loaded Lyman bullet number 375449, which was a gas check bullet that weighed about 265 grains with the check on it. I loaded it to 1750 FPS as fired across my little Chrony and used it to kill whitetail deer. It worked wonderfully well with one shot kills. I had previously tried to use the little 235 grain jacketed Speer bullet that I thought would expand on deer. WRONG!!! I killed two deer using it and had to shoot both of them twice. That Speer bullet was tough and abviosly made for the 375 H&H to be shot at normal velocity and at thick skined game.
