6mm ARC Upper Build

[Winkfish]

we are getting 2,700 fps out of a AR, with a Bartline 24" barrel. This is with factory Hornady 108gr ELDM. The best magazines I have found are from E-Lander. This has been very consistent velocity with over 1,000 rounds through it. I can share images of the rifle or groups if you want.

 

[JustMe2]

Thanks for the quick responses. I thought that was going to be the answers. I don't own an AR15, so was wondering about the cheap route. Guess I'll need to buy an AR15 upper and lower or bolt rifle. Thanks.

 

[spladi]

I built my upper using a heavy billet side charger from brownells, forget the brand. I used a 20" proof barrel. If that is your barrel choice be sure to get a jp bolt. I tried a brownells bolt and it really didn't match up well. Also I tried a jp spring system and light weight bolt that didn't work reliably. Great for 223 not so much for 6ARC. I ended up with a tubbs spring, h1 buffer and a full mass carrier. I'm running a slr adjustable gas block.

Since I played with the buffer system I haven't reset my dies, but with the light system I had to resize my Hornady brass 10 thousandths, with in my opinion is way too much for reliable cycling.

I have not had great luck with my handloads. I'm only getting 2530'ish. That was a node across multiple powders. I managed to push to 2600 but it was showing pressure and over 2600 I popped some primers. In the summer, I saw 2700 with factory, but it was leaving bad ejector marks.

All that said, I like the arc. It does everything I want from an AR better than 223. But it has been very a challenge to get all the bugs worked out for a rifle that can do both some competitions and some hunting. But it and my 6.5Creedmoor AR 10 are the ones that get shot the most.

I know that the 6 PPC (which is pretty close in case design as the ARC, Grendel, 7.62x39 etc.) operates at high pressure but the guys shooting it use about 65 - 70 grain bullets, heavier bullets would create higher pressures and lower velocity. I don't understand why the 6 BR. wasn't selected instead of the ARC. which can push a 105 to 2800 FPS +.

 

[Eric H]

we are getting 2,700 fps out of a AR, with a Bartline 24" barrel. This is with factory Hornady 108gr ELDM. The best magazines I have found are from E-Lander. This has been very consistent velocity with over 1,000 rounds through it. I can share images of the rifle or groups if you want.

What twist barrel are you using? 7.5?

 

[Winkfish]

What twist barrel are you using? 7.5?

Yes it is 1:7.5

I am getting upload errors when I attempt to add images today for whatever reason

 

[Eric H]

Yes it is 1:7.5

I am getting upload errors when I attempt to add images today for whatever reason

Was getting that yesterday.

 

[Zen Archery]

No coyotes came out to play but took a cool pic…

 

[Winkfish]

It is working now.

 

[Eric H]

View attachment 415579
View attachment 415580
It is working now.

How long to get your barrel? 24inch is custom.

 

[Winkfish]

Wait time on the barrel? It was some shenanigans with Bartline and my daughter. I had different plans for a bolt gun and they went down this rabbit hole. I think it took about 4 months to get the barrel and chamber work done. It is the "new" mod400 steel so they are claiming at least double the barrel life so we will see.

It is 24" in length and has a rifle +2" gas system.
The rifle will shoot. With Factory 108gr ELDM here is a 10 shot group at 100 yards. This is a typical group and it will shoot handloads either the 108 ELDM or Berger 108 just as well if not better. This is just pulling the trigger and going, no waiting between shots.

 

[Eric H]

Wow!!!

 

[Eric H]

Wait time on the barrel? It was some shenanigans with Bartline and my daughter. I had different plans for a bolt gun and they went down this rabbit hole. I think it took about 4 months to get the barrel and chamber work done. It is the "new" mod400 steel so they are claiming at least double the barrel life so we will see.

It is 24" in length and has a rifle +2" gas system.
The rifle will shoot. With Factory 108gr ELDM here is a 10 shot group at 100 yards. This is a typical group and it will shoot handloads either the 108 ELDM or Berger 108 just as well if not better. This is just pulling the trigger and going, no waiting between shots.

View attachment 415588

When you say "chamber work" I'm guessing it's not SAAMI spec.

 

[264MHC]

Impressive shooting for sure

 

[Winkfish]

It is a SAAMI spec chamber, I am using an older BAT machine barrel extension and JP bolt head.

The shooting is all done by my daughter who is 15. This is her rifle, that she primarily uses for PSR style shooting.