I chronographed some factory Winchester loads (45 gr bthp) which Winchester says delivered 4000 fps from their test barrel. I got a hair over 3400 fps out of the Striker (12" bbl) which was about what I expected.
I then loaded a bunch of cases from the factory ammo using a Winchester large rifle primer, a 55 gr Sierra bthp behind 34 gr BLC-2 (Hodgdon's max load). These loads chronographed at under 2400 fps, but Hodgdon predicted 3600 fps.
If I account for the shorter bbl at approximately the same percentage as for the 45 gr factory loads, I would predict a hair over 3000 fps. I've disassembled a couple of the loads to eliminate the possibility that the scale got moved somehow, but the charge weighed as expected.
Does anyone have any ideas about where the 600 fps went?
