+1.
Like the OP, I estimated my 18-in barrel rifle would shoot the ammo at 2670 fps, since factory pulished data for Hornady 75gr BTHP is 2790 fps. I sighted in the rifle at 100yds using a BDC scope. Then tried shooting 500 yd and 600 yd steel targets using the BDC lines, no hits.
Asked a buddy...