Contemplating 6mm ARC build

[entoptics]

Thoughts on this cartridge in a DI gun?

If I build, it would actually be a "longer range" M4 style rifle. I'm not looking for 1000 yd targets, PRS, or anything like that. First and foremost a practical fighting rifle, but also capable of harvesting "big" game out to 300 yds or so. Something good for Zombie Apocalypse, youth/novice training, and just plain old "fun".

Specs would be...

1) 7.0 lbs naked
2) Per #1, 16" medium to light contour bbl
3) Adjustable gas block
4) 75-105 gr projectiles. Ideally a good "cheap" light and fast option, and another heavier and higher BC bullet for hunting (e.g. 75 VMAX and 103 ELDX)

What I'm hoping to hear from the peanut gallery is...

1) Real world velocities from a 16" bbl with both lighter and heavier bullets.
2) Reliability concerns? Heard that magazines are a bit of a weak link...
3) Gas system length for 16" bbl (18" on up seems to be the only thing I see reviews about on the great Googles).
4) Brass availability and cost
5) Good powder choices
6) Any other ± that may come to mind.

I'm fairly experienced with AR building, and already have a donor rifle, so I'm not worried about "standard" stuff, but more about how the 6 ARC specifically behaves within the AR space.

 

[budlight]

I'm a long time 26 inch bolt gun 243 person. Then I got into AR-15's. When the arc came out I did a bunch of research. Because I have 1000's of 6mm pills. The problem was brass and case volume. So I started looking at ar10 in 243

 

[rpol98]

here's one of mine, 6mm ARC. Rainier 22" UM barrel (rifle+2 gas). slapped it on a lower from another setup, has an SSA-E trigger, good enough. However, currently assembling another dedicated FDE lower to go with this upper, will have a G HS-NM trigger.

I also have one with a Faxon 20" barrel (rifle gas):

sofar, using the ASC 6mm ARC mags (AR-Stoner from Midway), red follower, no problems, feeding has been absolutely reliable, no issues. Hornady "Black" 105gr ammo. will probably get around to trying out some of the 108 ELD soon, scored some of that. I had to open up the gas ports of both of the barrels by a few thousandths, no biggie.

The Faxon has an SLR Sentry-7 AGB, makes life easy. The Rainier, with its' .875" GB journal, couldn't fit the AGB under that slim low-profile rail.

 

[toeheadAR]

I was always excited about the 6mm round and its capabilities but at the time (a few years ago) I don't recall seeing manufactured ammo support for it so I had all the parts to build a .224 Valkrie. I ended up selling all of the parts shortly after. Now that 6mm arc seems to have manufacturing support and SOF units are using it I feel like this round may have some legs behind it. Hopefully, it keeps growing as I would like to build one in the near future. I can't really help with real-world experience but I think you're on the right track for caliber choice.

 

[WanderingGoatie]

I went 6.5 Grendel. The 6ARC seemed like it really needed a longer barrel to see the benefit. I've had good results on a pronghorn with a 123gr. I've also had great results on steel at 300 with great groups and lots of energy.

 

[toeheadAR]

What barrel length did you go with for the Grendel?

 

[WanderingGoatie]

18" Draco barrel (I was always curious about Draco's and they were something like half off). My buddy and I each put matching uppers together with the same components purpose built for MN deer hunting. Max range about 250-300, short for deer blinds, even with a suppressor. I didn't chrono but my dope chart has basic hornady factory 123gr hunting rounds at 2550fps. Really an enjoyable gun to shoot.