Looking for a upper that would extend the range for an AR.
The 6mm ARC seems to be a good candidate but I read of unsatisfactory accuracy experience when coupled to a AR platform (would be mounted on a Daniel defense lower).
Does anybody have some first hand knowledge?

quote:

Originally posted by armored:
but I read of unsatisfactory accuracy experience when coupled to a AR platform

Source?

Grendel

quote:

Originally posted by fritz:
Source?

My question as well.

Although realistically my AR-purchasing days are over, if I made an exception, one chambered for the 6mm ARC was what I thought of when I first heard of the cartridge. (Assuming as well, of course, that guns and ammunition availability and prices returned to something like pre-2008 levels. )

I did not earmark the articles and YouTube videos that talked about accuracy and mechanical problems with the ARC. I did note more than a few areas of concern thus this thread looking for actual user input.
This upper is a Christmas gift for somebody new to longer range shooting.
The ARC cartridge would need to show a definitive improvement over the 5.56 cartridge out of a 16" barrel to justify the ARC purchase.I'm looking at a 20" to 24" barrel option on the ARC.
The range I'm a member of has a 600yard range that I was looking to use this cartridge at.
I would eventually be reloading this cartridge.

My other choice is a 450 Bushmaster upper, but that would be a 200 yard or less "thumper" gun.

quote:

Originally posted by armored:
I did not earmark the articles and YouTube videos that talked about accuracy and mechanical problems with the ARC. I did note more than a few areas of concern thus this thread looking for actual user input.
This upper is a Christmas gift for somebody new to longer range shooting.
The ARC cartridge would need to show a definitive improvement over the 5.56 cartridge out of a 16" barrel to justify the ARC purchase.I'm looking at a 20" to 24" barrel option on the ARC.
The range I'm a member of has a 600yard range that I was looking to use this cartridge at.
I would eventually be reloading this cartridge.

My other choice is a 450 Bushmaster upper, but that would be a 200 yard or less "thumper" gun.

One member at my range uses the ARC. He was able to ring the steel handily and with authority at 500, when my 55grain 223 was barely audible and you couldn’t see the plate move (USPSA target AR500)

quote:

Originally posted by armored:
I did not earmark the articles and YouTube videos that talked about accuracy and mechanical problems with the ARC. I did note more than a few areas of concern thus this thread looking for actual user input.
This upper is a Christmas gift for somebody new to longer range shooting.
The ARC cartridge would need to show a definitive improvement over the 5.56 cartridge out of a 16" barrel to justify the ARC purchase.I'm looking at a 20" to 24" barrel option on the ARC.

I've watched 6mm ARC off and on for the last 1.5 years, since Hornady made it news. Initial reviews could be mixed, as some tried to hotrod it into a 6BR or 6Dasher. It's not -- the ARC is just a 6 Grendel, which isn't bad at all. Hornady's timing on the 6 ARC sucked, IMO COVID-related issues have hurt its growth and acceptance, maybe permanently.

The bad... 6 ARC suffers from bolt issues like every other cartridge that shoehorns a larger bolt face into a AR15 223 BCG frame. 6 Grendel, 6.8 SPC, 224 Valkyrie. Use cheap bolts, push your powder charge and the bolts will eventually show the results.

6mm bullets offer high BCs with reasonable weights. An AR15 can do a decent job of getting the bullets up to a speed that will do some good at distance. 6.5mm bullets are a bit too heavy to get up to speed. 223 bullets are a little constrained in bore size to get up to speed.

With a quality barrel, quality chamber, quality bolt, and proper assembly -- 6 ARC will hands down beat the accuracy of a 5.56-chambered AR15. Few AR builders use quality components in their 5.56-chambered guns to produce any great level of accuracy. A properly built 223-chambered AR15 will beat a 5.56 in accuracy.

6mm match bullets will be at least 100 points higher in G1 B.C. than anything in 223. This results in superior wind deflection at distance. The 223 bullets will fly flatter for a while, but the 6mm bullets will eventually catch up. The 223 bullets will go trans sonic well before the 6mm ones do.

I don't claim to have seen every article or video about 6mm ARC accuracy or function. But I've reviewed quite a few. I'm still considering changing one of my 223 ARs to 6 ARC, once that AR's barrel is toast.

The videos that gripe about 6 ARC's accuracy tend to have common themes. Second-tier components, especially the barrel. Fairly inexperienced AR shooters. Shooters with less-than-stellar technique -- trigger slap, marginal rifle support, marginal rear bag technique, visible breathing issues, marginal follow through, inexperience in calling wind. Understand that consistently shooting a semi-auto rifle with great accuracy requires great technique, applied consistently.

Your shooting friend will likely have a better tool for 600 yard targets with a high-end 223 with a 20" match barrel. Going to a high-end 6 ARC with a 20" to 22" barrel ups the game even more. Understand that a 24" barrel is a lot for an AR15. Also understand that 22" and 24" AR barrels perform better with a gas system length of rifle plus 1" or 2".

Thanks for your insights as always, fritz. Little chance that I’ll ever have a 6mm ARC rifle, but that’s good information.

Thanks to both of you.

Friend/fellow competitive shooter has a 22" 6MM ARC on a Bartlien barrel, Berger 105 Hybrids at a reasonable velocity. Shoots extremely well, feeds well. Day in and day out it'll shoot inside my 223 AR's. No surprise there, all things being equal using quality components/competent shooter a 6mm 105 class bullets is going to out shoot a 223 bullet in terms of consistency even over the heavy 223 bullets. We certainly see that in the bolt rifles. 22x47, 22 Creedmoor, 22BR, 22 Dasher will not hang with their 6mm relatives.

New to long range... either caliber in a gasser is going to be challenging at 600yds. For the cost of feeding it, a 223/556 upper might be a better way to go for your friend.

quote:

Originally posted by MikeinNC:
One member at my range uses the ARC. He was able to ring the steel handily and with authority at 500, when my 55grain 223 was barely audible and you couldn’t see the plate move (USPSA target AR500)

This occurs regularly when one varies calibers, steel size/thickness, and target distances. In your case, the 6 ARC has a heavy bullet that travels efficiently through the air. By comparison, your 55 grain bullet is rapidly bleeding velocity.

In a training course last year, I shot my 20" 223 AR15 next to guys with AR10s in 308 and 6.5 Creedmoor. We had relatively fixed 10" square plates of 1/2" AR500 on T-posts at 100 yard increments. At 400 & 500 yards, spotting hits with the AR10s was easy, but the plates jumped around so much that spotting impact locations was a challenge. We knew exactly where my poodle-shooter hits occurred. At 800 yards, my 75-grain impacts were really hard to see, even on freshly painted steel. Their impacts rattled the plate pretty well and chipped away a lot of paint.

Some of the regional matches here use A-frame rebar target stands, then hang the steel on a single 3" wide conveyor belt strap. The ease of determining the impact location depends on many factors. A moderate sized target at a few hundred yards might be spun so hard with a 140 grain 6.5CM that it's difficult to determine if the impact was on the left or right edge. Hit the same target in the same location with a 105 grain 6BR and all spotters should agree on the impact location.

Hit a thick IPSC target at 1000 yards with a 6.5CM and many spotters will state the exact impact location. With a 6BR the response might be "I think that was a hit, but the plate really didn't move. You might have hit it dead center." Add wind noise, and the smaller calibers at distance become a challenge. Spotting the splash for misses can be even worse.

Steel thickness matters, too. 1/4" steel rings better than 3/8" steel -- a louder "ting" versus a moderate "thunk". But thinner steel warps faster from repeated bullet energy, even when the impacts are below 2000 fps. Well below the 2400-ish fps level that generally is where a single hit starts to pit the surface of AR500 steel. For example, repeated impacts with 75 grain 223 at 500 yards slowly warped my IPSC 1/4" target. Just one impact with a 308 produced a shallow, but noticeable bulge on this 1/4" target at 500 yards. There's a reason JC Steel told me not to place 1/4" targets any closer than 800 yards with my 308 and 6.5CM, and that I should let the steel swing freely.