01-27-2019, 12:55 PM
DMC99999 Wrote:Hi all; I have a 20 inch Grendel barrel, and I have mounted a Primary Arms 4x14 x44 ffp scope on it. P.A says that for the scopes reticle to work correctly i need to get a 123gn bullet moving at 2650 fps. any Ideas where to start. I have looked around the net a bit but, have only found loads that will get me up to 2550fps. Any info would be much appreciated. Thanks
2650 fps? Not for 123 gr, more than likely no way to get there without breaking something. Not worth it.
The hottest load from Hodgdon reloading data for 123 pills only shown 2500 with 24" barrel. Similarly, Sierra 123 HPBT shown the same max load @ 2500 fps. Best is to work up load from below max, test it with your barrel over a chronograph. Don't rely on published data for velocity out of your barrel. In particularly when trying to use the bdc reticle from any scopes.
A little bit off topic - If you insist on using the PA scope's reticle substensions, do the math assuming a MV of 2580 out of their test barrel of 24", subtract 100 fps estimated loss for the shorter barrel, run a ballistic calculator using this velocity to find ballistic data. Acquire substension data from PA for your scope and try to match that to your calculated data with different zero distances. Most likely 200 yds zero would work instead of 100.