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Posted: 9/30/2014 11:04:33 PM EST
Recently built a varmint gun and took it to the range. Was disappointed with accuracy. Would hold about a 1.5" group at 100 yards. I could live with 1.5" groups, but every several rounds I have a flier in different directions about 2-3" out. Tried a variety of 55 grain factory .223 ammo, mostly PMC. The build is all new: Magpul stock and handgrip, DPMS .223 stainless fluted 20" bull barrel with crown, DPMS upper (lapped for barrel/torqued), Spikes Tactical lower, RRA two stage (polished) trigger, DPMS BCG, and a new, mid-grade Leupold scope (4X12) and rings (lapped/leveled/torqued). Ran about a dozen rounds, then cleaned it, repeated this 3 times, with cooling in between. Just plinking. Then got serious about accuracy. With fliers, holding 3" groups. I expected better accuracy. I currently have a standard, low-profile gas block with two set screws. Only one screw lines up with holes in barrel. Torqued both. Can't imagine this is stressing the barrel but I am not sure. Considering a clamp on, adjustable gas block. Have broken in a number of new ARs but never when I was seeking accuracy. Does it take a few hundred rounds in an AR before it settles down in terms of accuracy? Maybe I just need to plink with another 100 rounds or so and then go for group size. I will measure the chamber and hand load for it for my next trip to the range. Any opinions on the gas block? Any suggestions? Thanks.
Link Posted: 9/30/2014 11:19:09 PM EST
what twist, what trigger, was it rested

there are a ton of variables you left out
Link Posted: 9/30/2014 11:59:45 PM EST
I've heard some guys say a clamp on is better(for accuracy) but I have 2 rifles, that are capable of .5MOA, they both use set screw GBs and are pinned. I've heard a few guys say they can feel the set screws when the run a patch on a jag down the barrel. Not sure if this is BS or not but I've never experienced anything like that. Use Rocksett on your set screw and torque them to 15 inlbs.

Your trigger could be an issue but it's more likely ammo related. If you roll your own, don't chase velocity. Start low and find the sweet spot for that specific barrel.
Link Posted: 10/1/2014 12:42:22 AM EST
A few more things: the barrel is free floating, DPMS vented tube, 1-8 twist, target crown, Teflon black coated stainless. Trigger is Rock River Arms, two stage, breaks at 4.5 lbs. Pushing a patch through the barrel is nice and smooth but I can sometimes feel the gas port when I pass it. Scope is/was a new Leupold VX-R (red dot reticle). May change to a Burris AR scope calibrated to 55gr 5.56. If so, I'll load .223 to 5.56 ballistics...or close.
Link Posted: 10/1/2014 12:57:30 PM EST
Try some match ammo, 55-77gr until you find something that shoots the best.
Link Posted: 10/1/2014 2:36:11 PM EST
[Last Edit: 10/1/2014 2:36:33 PM EST by taylorjr]
Federal Gold Medal Match, 69gr SMK. That should be your benchmark.

Also possible there's a serious burr at the gas port. You'll just have to shoot that out.

Heat POI shift could be an issue. Let your barrel cool and take all variables possible out of your shooting.

Link Posted: 10/1/2014 2:42:10 PM EST
I've had AR's and M-4's show pretty erratic shifts in POI within the first 200 rounds. Some don't show any signs of this. I'd put a couple hundred rnds down range and then re-evaluate it with several types of ammunition of varying weighs of bullets.
Link Posted: 10/2/2014 12:25:34 AM EST
I'm going to run another 50-100 cheap rounds through it to see if it starts to settle down. Then shoot some 50 gr Hornady V-MAXs I just loaded. The only thing besides FMJ I had on the shelf. Will see how they go. After that will be some match bullets.

Thanks, all, for the advice. Very helpful.
Link Posted: 10/2/2014 2:25:30 AM EST
[Last Edit: 10/2/2014 2:35:40 AM EST by JesterGrin_1]
Just my Own thoughts but in a 1-8 twist I feel the 55Gr is a bit light. I would do as someone suggested and try some heavier rounds. Say 69Gr to 77 Gr. bullets and give them a go.

Also as noted. If you do reload your own then I would start at the bottom of the powder charges and work up .5 gr at a time. Say 10.O , 10.5 , 11,O like that. Do not use those charge weights it was just to show how to work up a little at a time. And work to the powder charge that gives the best accuracy. Do not worry about speed as that will take care of it self as Speed does not matter much if you can not hit what you are aiming at lol.

Or you can try what is called a ladder test. And there are tons of information on doing so.

Now this is not set in stone as far as bullet weights. As I know that heavier bullets are more expensive especially if you move to the more premium bullets. Thus if you plan to shoot mainly 50 Gr Varmint bullets or say run of the mill 55 Gr bullets then work up a load for them for general use and work up a load for a heavier bullet when you wish to get serious about accuracy for Hunting purposes.

Also do not get discouraged easy as when hand loading sometimes we get lucky real fast with a load and bullet combination that works while other times it takes some serious work and time.

This is my Cheap .358 Winchester Build with Home Cast Bullets and as you can see by the powder charges a little change can make a pretty big difference. And by the way they are all 5 shot Groups. :)

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