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Help needed any advice will help


Dre22

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Hey everyone, this is my first time posting on this forum, and I'm not to sure if this is the correct thread to ask this, but it seemed fit. I just built a DPMS AR-10 and the first time I took it out I was shooting extremely inconsistent groups, and when I say inconsistent I mean 10" groups at 100 yards. So I tried a whole range of ammo which didn't seem to help at all. Next I tried torquing down the barrel nut to 50'lb and that tightened the group to about 6". But no luck in improving beyond that. The barrel is a brownell barrel, I know its not a very high quality barrel but I feel like it should perform better than this. And my scope is vortex PST gen 2 5×25. I have yet to try mounting g the scope to another rifle to check and see if it's the scope, so that's still on the list. If anyone can give me some advice on how to fix it I would appreciate it very much.

Edited by Dre22
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Welcome! I'll start with the word police thing, you do not have an AR-10, AR-10 denotes an Armalite rifle, you have a 308AR, LR-308, DPMS pattern rifle. Seems trivial but when buying parts it can matter. 

What brand receivers? How is the barrel fit in the upper, tight, loose? I assume the headspace checked out? Check the usual suspects, loose mounting of the optic, condition of the barrel crown. Inspect an unfired round, after it has been fed, for any damage to the bullet. I'm sure others will be along shortly with more questions or answers.

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Welcome aboard -- you've come to the right place.

First thing we're going to need is a parts list -- every part you put into the rifle. If you bought an upper or lower complete, be sure to mention who built it.

Next, we're going to need to know what steps you took in assembling this rifle. Specifically, in this case, installation of the barrel. You said you went back and torqued the barrel nut to 50 lb-ft., what was it torqued to originally?

Agreed with jtallen83 -- double-check your scope mount and, if you haven't already, put some LocTite (at least purple, but I prefer blue) on the screws/bolts that secure the scope in the mount.

Edited by COBrien
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Parts list 

 Aero Percision Matching upper and lower reciever 

Brownell 20" 308 barrel 

geissele trigger

SLR adjustable gass block and tube

And originally I had the barrel nut torqued to 30'lb

I looked up all the torque ing specs online originally, for example vortex recommends 20"lb for there scope ring which I felt was ridiculous because I was able to slide the scope back and forth while it was in the rings. so I went back and torqued just hand tight I'm not sure if I did the right thing though.

I'm glad I came here I was damn near close to just giving up and buying a new barrel, but who know that might still be the solution.

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19 minutes ago, Dre22 said:

I looked up all the torque ing specs online originally, for example vortex recommends 20"lb for there scope ring which I felt was ridiculous because I was able to slide the scope back and forth while it was in the rings. so I went back and torqued just hand tight I'm not sure if I did the right thing though.

Something doesn't sound right there, 20 in Lbs should be tight enough you can't move the scope around. 

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4 hours ago, Dre22 said:

I looked up all the torque ing specs online originally, for example vortex recommends 20"lb for there scope ring which I felt was ridiculous because I was able to slide the scope back and forth while it was in the rings.

Bad juju here.  You buy the wrong mount size for the scope diameter?  I'm betting on 30mm scope tube (that specific Vortex you mentioned) and 34mm mount.  20 in/lb should have locked that sucker DOWN in the mount. 

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46 minutes ago, Dre22 said:

I made sure to buy the right size mounts 30mm tube and 30mm mounts

What brand of mount?  I have to go back to this, down here, vvv

1 hour ago, 98Z5V said:

 20 in/lb should have locked that sucker DOWN in the mount. 

 

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  • 2 years later...
  • 4 weeks later...
15 hours ago, micmacman said:

he maybe has the the ring caps backwards , some caps have a right and left , try flipping them

Again, the OP hasn't been here for 3 years. 

However, LaRue ring caps are like that, but they're mirror-images of each other - so it wouldn't matter which one you put on the left, or the right.  Anybody making something that is specifically left and right, and can only be that way - that's a pretty fucking stupid design. My Humble Opinion. Love it or leave it.

Edited by 98Z5V
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15 hours ago, 98Z5V said:

Again, the OP hasn't been here for 3 years. 

However, LaRue ring caps are like that, but they're mirror-images of each other - so it wouldn't matter which one you put on the left, or the right.  Anybody making something that is specifically left and right, and can only be that way - that's a pretty fucking stupid design. My Humble Opinion. Love it or leave it.

the design is one because of the angle of the mount ,nothing to do with stupid , but when the caps are off it is indistinguishable that there is a right of left until you try and seat the cap it will not conform to the tube properly 

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8 hours ago, micmacman said:

the design is one because of the angle of the mount ,nothing to do with stupid , but when the caps are off it is indistinguishable that there is a right of left until you try and seat the cap it will not conform to the tube properly 

So, instead of building the MOA cant into the base, they built it into the rings?...

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