New 6mm Advanced Rifle Cartridge

[Gtscotty]

So what is the powder everyone seems to have settled on for the 108 grain loads? I am about ready to start loading for mine. I finally have depleted the factory ammo I bought for barrel break in and learning the platform a little more. I see AR comp for the 90ish grain loads. I am sitting on a full case of 108 ELDM to start load development.

With the factory Hornady 108 I am getting around 2670 for velocity with the 20" Proof barrel. If I can keep it around there I would be happy.

I think most folks are running LVR, especially if you are looking to match factory velocities. Other similar options would be CFE223 and AA2520. Personally my load with the 108gr is 29.3gr LVR, 450s, 20 thou off, matches up to the factory velocities fairly well, a little faster in warm temps. The 29.1gr to 29.5gr range for LVR has been a sweet spot for me across several bullets in the 95gr to 108gr weights.

Attached is some data Sierra sent me, doesn't include LVR, but has CFE223 which is similar, and for the 100gr and 110gr loads, matches up to Hornady data pretty well. The 107gr data is weirdly low compared to the two other weights bracketing it though.

 

[LRRPF52]

Interesting video from Wade at Texas Predator Hunting. He was doing high pressure test in a pressure test rig, running things way above SAAMI, and finally experienced firing pin aperture erosion, flaking, causing FTFire, FTExtract.

Hasn’t had any issues with bolts under normal operation for years.



When I broke bolts in 5.56, I started having FTFeed, because the bolt cracked at the cam pin hole.

I’ve been shooting Grendel since 2009 across a wide variety of barrel and gas system lengths, tons of factory and hand loads, still haven’t broken a bolt or extractor.

I’ve been shooting the 12” CLGS Suppressed as my go-to since 2017, but I take the 17.6” Lilja and 18” LaRue along with it usually as well. Things just run.

 

[putput30]

Interesting video from Wade at Texas Predator Hunting. He was doing high pressure test in a pressure test rig, running things way above SAAMI, and finally experienced firing pin aperture erosion, flaking, causing FTFire, FTExtract.

Hasn’t had any issues with bolts under normal operation for years.



When I broke bolts in 5.56, I started having FTFeed, because the bolt cracked at the cam pin hole.

I’ve been shooting Grendel since 2009 across a wide variety of barrel and gas system lengths, tons of factory and hand loads, still haven’t broken a bolt or extractor.

I’ve been shooting the 12” CLGS Suppressed as my go-to since 2017, but I take the 17.6” Lilja and 18” LaRue along with it usually as well. Things just run.

I saw that. I like how Wade is constantly pushing the arc to its maximum to see where it will fail so we don't have too. I want him to push a more exotic bolt like the geissele to its limit to see the differences between a standard vs exotic bolt material. Curious if the geissele platforms can be pushed to 62k or are they just like any other standard AR.

 

[LRRPF52]

I’m not an advocate of chasing pressure to try to eek out marginal gains in performance.

I quickly learned to look at load manuals and find powders that generated top-end velocities, but with lower pressures. Let the powder do the work rather than trying to get brave on the bench.

Maybe that’s why I’ve never broken a Grendel bolt, but have velocities that are higher than factory ammo as a general rule, but 2500-5000psi less than SAAMI MAP.