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I built my sons 6mm ARC on a lefty Stag upper, Odin 21 in rifle plus gas, reg carbine lower, he is 9 yrs old so I need length of pull short. I keep seeing everyone getting .5 moa? I shoot PRS type matches w bold guns and I have used an ar10 in 308 years ago when I started. It took 250 rounds to get my 308 to consistently group under 1moa. I am using Hornady match ammo, and My rifle is no where near .5. I played with the gas system, as I am running a can on the barrel. Still my best was 1 MOA..... Do I need a rifle buffer tube.....any suggestions? I don't see this thing getting .5.....
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the rifle buffer won't help. And if you want to swap to a heavier buffer, like H1 or H2, worth a try, but we don't have any info to look at on your setup that would suggest that.
What are the symptoms, which factory load are you using, for factory there's 103 eldx, 105 and 108, which ones have you tried.
Lots of AR barrels in grendel, and 6Arc, need about 100 rounds before they settle down, and you typically gain about 50 fps by then.
for my 20" monster barrel the 108 shoots the best, but a faxon 20" Ihad did the 105's better.
Are you a reloader, do you have a chrony?
For short lop, the carbine stock offers that but a rifle stock, not.
there's also trigger, what kind and what # of pull, and for scope, what cheek rest, most times you need an elevated cheek rest for the scope/cantilever setup.
For your son, a 90/95 gr handload will be perfect, no recoil and good for targets or hunting, whichever. 90 eldx, 90 tgk, 95 bergers (any), I've even got the 95 nosler BT's working in my 20".
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Today was the first time shooting it. Im shooting the 108 match from hornady, I tried the 105 Blacks, mine liked the 108s the best. My trigger is a Geissle, 3.5 lb
My gasser 308 needed some seasoning too. That is what I am trying to figure out. I didn't chronograph due to factory match loads and all Im trying to do is break this barrel in and get it zero'ed. I do reload for my bolts, I shoot Prs, with my bolt guns. I wanted a rifle my could start competing with, the ARC seemed like a great choice.....but not at 1.5 MOA....I will run some more rounds down it and continue the break in process. It is erratic. I will center punch one, then one will be an inch high, then the next one goes in the same hole and inch high, then back to zero. I am going to try it without the can too. I have an area 419 Hellfire for a break.
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Stonehenge on here shoots some competition with his Arc and has some posts on here, you might pick up some insights from him also...
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03-26-2023, 05:10 PM
(This post was last modified: 03-26-2023, 05:16 PM by pmc847.)
Make sure your barrel nut is torqued to spec and make sure your hand guard is not touching your gas block. Your barrel to receiver might not be matched/squared to each other. I lapped my receiver face with Brownell's tool.
https://www.brownells.com/tools-cleaning...ping-tool/
The barrel extension (od) to receiver (id) fit is important too. Should be a snug fit not loose.
Check scope mounting also.
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pmc847 made all the suggestions I was thinking. A heavier buffer can help a tiny bit, but if your ejecting the brass at 3:30- 4:00 I wouldn't increase the weight. With factory ammo most are getting 3/4 to 1 1/4 MOA, there's a a few on this site getting better with factory ammo but I don't think it's the norm.
