10-19-2022, 02:57 AM
I've got an AR cycling subsonic 6.5 Grendel load. It works well out of my 12" PSA with Superlative Arms adjustable gas block and H2 buffer. I did a lot of digging around and landed on this. It was not my development so I don't fully understand some of the reasons for doing some of the things. And here's the usual disclaimer...use at your own risk...do your own research...work up (technically down) your own load.
You'll want to make sure you have sufficient clearance in your chamber for the heavier walled AK brass to expand and release the bullet.
I started with new 7.62x39 brass sized for the Grendel, enlarged the flash holes to 9/64", and primed with large rifle magnum primers. Charged 5 rds each at 15, 14, 13.5 and 13 grains of IMR 8208 Xbr. Set the Hornady 160 gr RN at 2.220" COAL, no crimp.
I started with the chronograph, unsuppressed, with the heavier charges first, at 50 yds and a big piece of cardboard watching for any keyholing and making sure I had impacts. At 13 grn I had keyholing, 13.5 was possibly a little unstable, 14 and 15 grn looked good. The 14 grn load I settled on ran 1024 fps. I then ran some rounds suppressed (Ultra 7 30 cal) and tuned the gas block till full function and last round hold open was achieved. My unsuppressed supersonic loads and my suppressed subsonic loads both run at 1.5 turns open...suppressed supersonics run 1 turn open.
You'll want to make sure you have sufficient clearance in your chamber for the heavier walled AK brass to expand and release the bullet.
I started with new 7.62x39 brass sized for the Grendel, enlarged the flash holes to 9/64", and primed with large rifle magnum primers. Charged 5 rds each at 15, 14, 13.5 and 13 grains of IMR 8208 Xbr. Set the Hornady 160 gr RN at 2.220" COAL, no crimp.
I started with the chronograph, unsuppressed, with the heavier charges first, at 50 yds and a big piece of cardboard watching for any keyholing and making sure I had impacts. At 13 grn I had keyholing, 13.5 was possibly a little unstable, 14 and 15 grn looked good. The 14 grn load I settled on ran 1024 fps. I then ran some rounds suppressed (Ultra 7 30 cal) and tuned the gas block till full function and last round hold open was achieved. My unsuppressed supersonic loads and my suppressed subsonic loads both run at 1.5 turns open...suppressed supersonics run 1 turn open.