Hornady factory 123 gr A-Max and V-Max gets approximately 2670 FPS in my 24" Heavy Barrel with great accuracy. Trying to duplicate the accuracy and velocity of Hornady factory I use Hornady brass, RP 7 1/2 primers with AA2520 powder. My favorite is 30.2 grains of AA2520 powder, 123 A-Max seated the same oal as factory at 2.244"-2.246". Not maximum but work up to this level. Sierra 123 HP match shoots nearly the same with the same powder charge. Lapua brass gives approx. 50-70 fps less than using Hornady brass. CCI 41 primers shows 20-25 fps more velocity than RP 7 1/2 primers. Several good powders for 6.5 Grendel but I use AA2520. Consult all reloading sources. I did purchase Hornady factory ammo as it shot so well plus brass was once so expensive that it was cheaper to buy loaded and save the brass. Not so much now as brass is less expensive. Haven't tried the latest Hornady bullets as I still have a good supply of A-Max bullets.