Tips for accurizing an ar...

coyotekilla83

coyotekilla83

New member
So, I went with a bear creek side charger ar, 20" gunner profile, 416r barreled upper.

Aero precision lower, magpul prs light butstock, magpul k2 grip, cmg 2.5 single stage trigger.

Currently getting about inch groups at 100 with handloaded 95 vmax.

What have you all gained by shimming the barrel / receiver fit, or other tips and tricks to accurize an ar platform?
 
Squaring the receiver face turned one of my first builds from a dud into a great shooter. Mike Milli of Dtech suggested that and took care of that first one for me for the cost of shipping which was pretty awesome. Since then I acquired a lapping tool and have squared all subsequent builds before putting them together so I can't give a before and after. He also suggested bedding with loctite between the extension and receiver.

Beyond that it's mostly barrel and load, assuming a good trigger and rigid handguard. If you're using a set screw gas block be careful not to over-tighten the screws. I much prefer clamp gas blocks.

My 20" Stoner (bca) Grendel barrel loves the 95 with 8208. Also loves the cheap PSA 123 grain black tip factory ammo.
 
204 AR said:
Squaring the receiver face turned one of my first builds from a dud into a great shooter. Mike Milli of Dtech suggested that and took care of that first one for me for the cost of shipping which was pretty awesome. Since then I acquired a lapping tool and have squared all subsequent builds before putting them together so I can't give a before and after. He also suggested bedding with loctite between the extension and receiver.

Beyond that it's mostly barrel and load, assuming a good trigger and rigid handguard. If you're using a set screw gas block be careful not to over-tighten the screws. I much prefer clamp gas blocks.

My 20" Stoner (bca) Grendel barrel loves the 95 with 8208. Also loves the cheap PSA 123 grain black tip factory ammo.
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Never heard the gas block advise, thank you. Currently the tube is removed and bock reversed, using it bolt action style. I like to shoot suppressed, and that keeps your ammo way cleaner.
 
crapshoot said:
Then what's the point of an AR?
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Beretta gets 1,300 for a brx1. Savage gets 1,100 for an impulse. I have about 580 in this build. Barrel alone on the brx1 is 700 I think.

Plus, pa doesn't let me use a semi for deer, so I can't leave the gas tube on it for using it there. But, if I want to make it semi, for fun or varmits, I can.

I kinda thought it would be an ideal platform to play with. Could be an ideal 1 gun solution for hunting deer, varmits, targets, or self defense. A very adaptable platform with alot of modular components.
 
The #1 thing you can do is just pick a quality barrel. You can get lucky with cheap stuff, but a good cut rifled barrel like Bartlein, Krieger, etc puts you way ahead.
I always square the receiver face:


And bed the barrel extension with Loctite 620:


And make sure the gas tube is aligned as close to perfect as you can get:


Also, I don't have one, but my research makes me believe that using a monolithic or semi-mono upper receiver, where the handguard attaches directly to the upper, and not the barrel nut can help. Especially when your shooting position changes pressure on the handguard, for example a bipod at the far end of the handguard vs a tripod or bag near the mag well.
 
SupressYourself said:
Also, I don't have one, but my research makes me believe that using a monolithic or semi-mono upper receiver, where the handguard attaches directly to the upper, and not the barrel nut can help. Especially when your shooting position changes pressure on the handguard, for example a bipod at the far end of the handguard vs a tripod or bag near the mag well.
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I want to try one of these myself. That slight poi change like in your example is my biggest problem with ar's.
 
'monolithic or semi-mono upper receiver, where the handguard attaches directly to the upper, and not the barrel nut can help' Never heard of such a thing. Only error is change in sight (upper) vs barrel bore. They all attach to the barrel nut. Have to actually bend the upper (at the barrel nut) for that to happen, assume a free-float H.G. Quit Swartzeneggering the gun. The only effect locktite and lapping can have is to solidify the barrel/upper joint to REDUCE any barrel harmonics, attempt to make the upper/barrel a 'solid' piece.
 
popper43 said:
'monolithic or semi-mono upper receiver, where the handguard attaches directly to the upper, and not the barrel nut can help' Never heard of such a thing. Only error is change in sight (upper) vs barrel bore. They all attach to the barrel nut. Have to actually bend the upper (at the barrel nut) for that to happen, assume a free-float H.G. Quit Swartzeneggering the gun. The only effect locktite and lapping can have is to solidify the barrel/upper joint to REDUCE any barrel harmonics, attempt to make the upper/barrel a 'solid' piece.
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Well, here's some light reading then: AR Positional POI Shift Test
 
I had a Savage MSR10 that the handguard screwed directly to the upper receiver. It shot around MOA but could shoot sub MOA with 95 gr. v max. I sold it because I didn't like the little 18 inch barrel & got a good return on it. For me it's all about the barrel, trigger, ammo and if I put any torque on the gun.
 
If you have a 10# rifle, 1/3 of the weight supported by the hand guard (1/3 on the 'handle, 1/3 on the stock), how much 'downward' force does the 'operator' provide to bend it at the barrel nut?
 
popper43 said:
If you have a 10# rifle, 1/3 of the weight supported by the hand guard (1/3 on the 'handle, 1/3 on the stock), how much 'downward' force does the 'operator' provide to bend it at the barrel nut?
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You don't need to apply any force. Nothing is "bending", but there is a minute amount of flex inherent in the design, which is all it takes to change poi. Try it out for yourself. Shoot a group at 100 yards with a bipod at the far end of the handguard. Then do the same with a bag right next to the mag well. Longer handguards are likely to exhibit the issue more as 'lever physics' are in play.
As long as you present the rifle the same way and have it zeroed that way (for example you always shoot off a bipod attached in the same spot), it's not much of an issue.
 
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My first "coyote" ar was a super accurate 223 AI. I'd get these crazy good groups right on target at 200 off the bench. Then go hunting with a bipod and shot over the first couple coyotes I called. I finally figured it out and was as surprised as the non believers here, everything I read said a free float tube fixes all. Keep in mind this was 15 years ago and the state of the art with AR builds wasn't yet what it is today.

To the point of being heavy handed, you probably could make the point that pulling it hard into your shoulder off a bipod would change the stresses on the upper/tube as there would be some downward force there as well.

The biggest takeaway is that a more rigid set-up is never a bad thing for a build you want max accuracy and versatility. I've yet to try the mono's, but have noticed that my old DPMS thicker receivers, my 30 RAR receivers which are heavier/thicker, and my G2 rifles are less prone to this than the standard m4 forged receiver.
 
There was a good article on Accurate Shooter site about making an accurate AR rifle. Not sure if its still there or not. It was under the "Bulletin" heading at the top of the page.
 
Barrels are free floated and stocks are 'bedded' to create a platform that has the effect of a tube supported only at one end, reducing 'harmonics' effects. Any 'bending' creates a problem. Nothing new. Bad fit and sloppy tolerances can be 'bandaided'. Most aren't that sloppy.
 
If you want an accurate one, put on a quality barrel with a quality trigger and square the face of the receiver. I have built quite a few that will consistently shoot .5 MOA or better groups. You must use quality parts though if you want that.
 
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