I’ve seen a few (maybe 10 or so) 6ARC rifles come through the courses over the last year and a half. Doesn’t sound like a lot but a typical class being 1000-1500 rounds so collectively I’ve watched about +10k slung down range.
…And I’m to the point now where the first thing I say to a student who shows up with a 6ARC is “well let’s see how far you make it”.
Note 6.5 Grendel shooters pretty much get the same treatment.
Observations
- Something about 6ARC factory (Hornady in particular) just seems so much dirtier than 5.56/.223, I typically see guys go right around 400 rounds before reliability becomes an issue, suppressors only seem to exacerbate the problem naturally.
- Magazines can be temperamental, especially with higher capacities. So choose wisely.
- Overall accuracy seems to be pretty good with factory match ammo. 3/4-1 MOA is typical.
Conclusion
- Like the 6.5 Grendel I don’t see the 6ARC in an AR platform ever being as reliable as 5.56, feed geometries being what they are. Literally everyone who’s ever brought one to our class has said the same thing “I’ve never had any problems.” But then again, most shooters never really pushed their guns hard.
- The flipside is the accuracy and the external ballistics particularly once you get beyond 600 yards, makes the 6ARC juice worth the squeeze.
I’ve been attending, RO’ing, coaching, or running carbine courses and long range events for just shy of 30 years now. That includes SOTIC MTT, European Coalition partner Sniper Instructor Courses, day-to-day CQM and CQB across 7 different units in the 1990s-2000s, 3-Gun, years of competition and training up for military team sniper matches, and the precision rifle matches that eventually became formalized as PRS.
With a lot of the civilian LR and DM courses, I’ve seen a lot of 6.5 Grendels since about 2013, including my own DM/LR courses. At some of the 3-day events, the firing points look like a support-by-fire position from back when I was in Weapons Squad with the belt-feds where dudes ran multiple 25rd mags in UKD reactive target arrays with hundreds of targets available to detect, range, and shoot. I primarily use a huge range complex in Utah that blows away pretty much every MPRC I saw across the world. It took me years to become familiar with all the ranges they have there, and I’m still discovering more each time I’m there.
I’m trying to recall any notable malfunctions with 6.5 Grendels, and am drawing a blank other than a pre-production experimental magazine that was sent to me to test in 2014. I loaded some longer COL 123gr A-MAX that didn’t clear the front, so they dragged and induced FTFeed.
Other than that, they have been running great. Most of these events are in Mountain West High Desert in Idaho, Utah, and New Mexico.
I have seen guys try to show up to carbine or DM courses with DIY 5.56 builds with slip-fit gas blocks, weird low-dollar parts cobbled together, or lubed with Frog Lube. They didn’t run well at all, but any reputable AR-15 will just run like a raped ape when lubed well, run known ammo, from good mags. I definitely haven’t seen 6.5 Grendels burnt down like 5.56 in high-volume CQM though, but typical for what you would see in a 250rd/day precision rifle. We shoot more for night iterations.
Based on everything I read about 6.5 Grendel, I should be seeing malfunctions every range trip, broken bolts, crappy mags, etc., but I just don’t. I’ve been shooting it a lot since 2009, and now have at least 7x 6.5 Grendel ARs. I have primarily shot my 16” MLGS AA barrel DIY build initially, then my 17.6” Lilja, 18” LaRue, and I’ve spent the past 6 years focusing on my 12” suppressed Grendel.
According to all I know about AR-15s, I should be having the most trouble with the 12” CLGS suppressed, but it and the twin I built of it have been running like raped apes for 6 years now.
Things I do differently with my approach to an AR build:
1. De-egde, blend, and polish the barrel extension
2. Chamfer the ejector so you don’t have right side presentation feeding issues
3. Seal or press-fit the gas block and gas tube
4. TDP carriers or carriers with good tri-bore internal diameters
5. Pre-check and measure the chambers for dimensional conformity to 4 different types of dummy cartridges I have
6. Gas tube alignment so there isn’t clipping
7. Receiver set in-spec for mag catch datum, carrier raceway ID
8. Gas port dimensions have to be correct, otherwise the gun will short-stroke or cycle too fast
9. Action spring weight needs to be dialed-in. For the 12” CLGS, I’m using an increased power spring.
If you approach a 6.5 Grendel like a TDP Mil-Std blaster, with a proven set of specifics for the differences in the barrel and bolt, you will have a reliable gun. Most of the manufacturers of parts out there don’t adhere to anything like that, couldn’t care less about a TDP, as long as their products look familiar to buyers who then purchase their VISMODs. I wouldn’t trust any company who can’t even build a remotely-TDP AR-15 in 5.56 to do anything with variant cartridges. There is a serious lack of competent engineering, QC/QA, and basic math skills in most of the smaller companies.
Critical things to the success I’ve been seeing with CLGS suppressed 6.5 Grendel, aside from the above are:
* Monster logo bolts, O-rings removed from under the extractor (Crane O-rings were a band-aid for the initial heavy SOCOM barrels with tight chambers, CLGS, shooting NT4 KAC cans with no way to compensate for the increased cyclic rate. No need for them on a correctly-timed gas system, which I adjust with the Bootleg Carrier)
* Bootleg Adjustable Gas Carrier
* Extra power action spring
* Factory brass-cased ammo
I’ve had guys come through with Wolf steel case and not have problems either, but I personally shoot brass-case ammo.
One thing with the 6mm ARC is that Hornady moved the shoulder back .030”, and it has a narrower neck and ogive of course, so transitioning through the barrel extension teeth after the feed ramps can be an issue for some guns. It takes a dedicated and competent engineering approach to get mag feed lip geometries correct. Look at how many decades we’ve been chasing that with 5.56x45.
I’ll have to ramp-up my round count to proof my set-ups. We’ve done some high-intensity CQM drills for fun (1-5) with suppressed 12” Grendel, but not all-day burn-downs. Your round count is indicative of what I’m used to with CQM, not LR.
Imagine you gave them a couple million dollars and 700 acres of remote wilderness and said “build a training facility to support the current requirements to actually push Mil/LE. organization to their full potential without any of the bullshit…and also open it to the American man because yes that’s a dollar but more importantly that’s a rifle behind every blade of grass.”
