The Buffalo Bore Load has a gas check that eliminates much of the leading.
I have chronographed this load in both my 2" M60-7 Chief's Special (1025 fps) and in my 2" Colt Detective Special (1040 fps).

I have also chronographed the Remington 158 gr. +P (FBI load) out of the 2" Chief's and I have averaged 775 fps. The Speer Gold Dot 135 +P out of the same gun was 890 fps.

I have also tested the Buffalo Bore NON +P standard pressure 158 grain lead bullet out of the 2" Chief's and it averages about 860 fps. which is about 10% more than the Remington +P FBI load.

Chief38