03-30-2021, 05:47 PM
Normally the cooler temperatures produce less pressure/velocity. Recent lots of Hornady Black show less velocity than the earlier production 6.5 Grendel 123 grain A-Max. Without shooting two rifles on the same outing using the same chronograph with the same ammo it is hard to know for sure using an optical chronograph. I think Id trust a lab radar or Magnetospeed chronograph more than an optical chronograph.
Your velocities seem a little low for a 20 barrel but if the ammo looses about 1 FPS per lower degree of temperature your still getting low velocity for factory ammo. In my 20 Shilen I got right around 2500 FPS with 123 grain SST on a 70 degree day using a magnetospeed chronograph.
With my 16 J&T the velocities were lower than expected regardless of ammo.
Your velocities seem a little low for a 20 barrel but if the ammo looses about 1 FPS per lower degree of temperature your still getting low velocity for factory ammo. In my 20 Shilen I got right around 2500 FPS with 123 grain SST on a 70 degree day using a magnetospeed chronograph.
With my 16 J&T the velocities were lower than expected regardless of ammo.