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Chillywig

AR accuracy issue with white oak 18" Rifle SPR Barrel

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Put a gun together with good components but have had a few problems. Now working on accuracy. Have shot my 77smk serivice rifle loads that shoot sub 1/2 moa out of a RR NM gun that shoot well over an inch @ 100 in this build. Tried some Hornary 68 and 73 gr factory match loads that shoot over an inch too. The WOA barrel probably has about 150 rounds thru it. I started thinking the barrel should have settled in by now and am wondering if my hand guard and muzzle device are making contact when shooting. 17.5 in hand guard on a 18 barrel. The only muzzle brake/suppressor mount that would let me attach a can and clear the hand guard is a YHM mount. Have about 0.0790 clearance between the brake and hand guard. Whats the chance these are hitting causing my poor accuracy issues?

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Maybe try taping some paper wrapped around the back of the brake between the hand guard and brake to see if any marks are left after shooting it. I’m not 100% this will work but I figured it would leave some type of indent on the paper. That’s very little clearance and with the extra weight of the suppressor on there I would be surprised it wasn’t hitting the hand guard.

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Posted (edited)

I think the quickest way to start diagnosing would be to shoot it with nothing attached. Process of elimination. If it still shoots poorly, then go down the rabbit hole. Lots of reasons for an AR to have accuracy issues. Ammo/Bolt/Gas/Receiver Fit/Barrel Torque/Etc/Etc...

 

Good luck!

Edited by Delfuego

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One of our rifles with a Odin Work ultra-lightweight barrel that shot sub moa, went to pieces when I put a tighter handguard on there.  I switched back to a roomier Samson Evolution handguard and it shot sub moa again.  That same handguard works fine on a different rifle with a heavier barrel profile.  I figure that lightweight barrel whipped too much and the gas block was hitting the handguard.

 

If you shoot a 60 or 70 round stage in a match those slimmer handguards get to hot also (or more properly are closer to the heat), like getting a burn hot, FWIW. 

 

I agree with the other poster, process of elimination.

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I would guess thats too close.

 

Take the handguard off and see if there is rub marks on the brake or the inside of the handguard.

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If you find that the accuracy doesn’t get any better with the hand-guard removed. I would check your barrel nut torque next like others have said and maybe try tightening it a bit more.


Sent from my iPhone using Tapatalk

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Finally got out to shoot this again without the brake installed. It shoots way under an 1" now - ragged one holes groups with my 77smk loads. I did notice that as the gun warms up the groups do open up a bit but still under MOA. 

 

I assume a bit of POI and group size shift is to be expected from most every gun as the barrel gets warm?

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Finally got out to shoot this again without the brake installed. It shoots way under an 1" now - ragged one holes groups with my 77smk loads. I did notice that as the gun warms up the groups do open up a bit but still under MOA. 
 
I assume a bit of POI and group size shift is to be expected from most every gun as the barrel gets warm?

Yes that is normal unless you said it was 6-12 inches different. Any update on what you are going to do next to gain clearance?



Sent from my iPhone using Tapatalk

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Posted (edited)

Ended up just cutting off a bit of the rail and put some black paint on the end to cover the cut. Cheaper than buying a new one plus the handguard and receiver set is cerakoted the same color. Its a shooter!  300 yard test target with 69 sierra MKs

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Edited by Chillywig

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was going to ask with the twist rate was but looks like you got it figured out. 

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16 hours ago, CJW3 said:

was going to ask with the twist rate was but looks like you got it figured out. 

It's 1 in 7 

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