I use a 55gr. Sierra HPBT . But all so use mine to squirrel hunt with, a reduced load. 40 gr . Sierra HP , 4.0 grs. of 700 X, cci 500 primer. About 1400FPS. I have a Remington 700 and it is a very good squirrel gun. When I can't find 22's , I can steal hunt with this.