The ammo loaded with the 77 grain Nosler OTM is from the original ar15.com special group purchase. The rounds loaded with the Sierra 77 grain MATCH HP are Black Hills 2nds purchased from Cabela's.
Rounds were chronographed using an Oehler 35-P chronograph. Muzzle velocities were calculated from instrumental velocities using Oehler's Ballistic Explorer software. All strings of fire consisted of 10 rounds.
Colt 20" A2 1:7" twist
Colt 16.1" M4 1:9" twist
Colt 14.5" M4 1:7" twist
For additional comparison I have chronogrpahed 6 different lots of 77 grain Federal Gold Medal ammo. The combined average muzzle velocity of all six lots was 2577 fps when fired from the same Colt 20" A2 barrel.
Good info, thanks for the work.
I still have some of that Nolser MK262 ammo on order. Been waiting about 2 years now on it. I wonder when it will come in...