Yeah, I have a fixed gas block. I will try the higher Benchmark loads and also try H335.
Make sure your gas block is aligned correctly, if adj open it to max, is your spring is correct? I think it's 28 coils for carbine and 30 for a rifle(look it up). Always start with a regular buffer and spring. Then try a H2 buffer if you want. Look at where the bass is ejected to. You want 2 to 3 oclock. More forward is over gased and 4 to 6 o'clock is under gased. Even a minimum load should cycle the weapon. So going to a higher charge weight is the wrong answer, you need to address the cycling issue first.
Any load over 2450 fps, <15 fps ES, and good moa is a winner. I've shot pretty much everything but AR comp and only cfe223 got over 2500 fps from a 20" barrel.
I've tried H335, 8202, TAC, A2520, benchmark, Leveraction, Varget, and cfe223, all with a 123 grs-smk's/sst/Nos CC's and a little with 130 gr otm's. I was just banging steel, not hunting with my 6.5 Grendel. For hunting and shooting under 400 yards, I'd use 8208 and a 120 Nos bt. Start at mag length, find the charge weight with a 1 or 2 shot ladder test, find a speed node(SN), and then load that weight and test seating depths to find the Accuracy Node/AN.
But am trying some n133 I just got, soon, am gonna throw together another Grendel for just hunting. I'll say it again, Benchmark went from ok to over pressure fast. So I gave it a pass. H335 would be OK to, and about as fast as 8208, and as temp stable, about.
Another thing, always check/trim your 6.5 Grendel brass. It stretches a lot. I've had to "mortar" a AR to unstick a stuck live round on more then one occasion. Mostly others while rso'ing. I learned the first time. I over trim by 5-10 thou usually and can get more then one firings in all other calibers, mostly bolt guns. Just checking a few cases before loading. Not with a AR 6.5 Grendel, check every round, every time. I've found that locking a caliber at the max case length and passing every case through it stops the issue of stuck cases.
I'll let you know if I find N133 to be magical. I'll be testing it and 8208 side by side. With 120 bt, when they come available.
