I worked up some sub loads this A.M with Hornady 208 Amax & some 195 BTHP I had laying around thru a 8.5" AR barrel w/.095 gas port size.I am getting 2250 FPS average with H110 with the hornady Vmax 110gr. I have got 2190 out of Accurate 5744 with Remington 150gr accutip.
They traveled @ 1055-1066 fps using Accuarte 1680. There never was enough energy to push the bolt back far enough to hold the bolt open.
Tried another upper 9.5" barrel, different barrel mfr, gas port 10 thousands bigger and the bolt held open after every single fed shot.
Any other powders you guys use other than A1680 & H110. I used them both.