Will Barrel Nut Shims Affect Accuracy?

[CNJarvis]

I’m putting together an upper with a WOA 20” Predator bbl and trying to decide on what handguard to get.

Several of the handguards I’m considering install with shims behind the barrel nut that are used to time the handguard. Will the use of shims between the barrel extension and the barrel nut have any detrimental effect on accuracy? I’m inclined to think that it might.

 

[JoeBUtah]

Seems like my WOA barrel build last fall took shims. Shoots sub moa most of the time. When it dosen't I'm sure it's the loose nut behind the trigger that goofs up the shot...

 

[10ring1]

Bought my first woa Sdm and i had to shim it as well. I will be shooting a 5x5 in the spring but it shoots 77gr tmks better than any barrel I own

 

[Bigjake83]

If done properly it will have zero effect on you're accuracy, KAC uses the same technique due to the fact that their Barrel nut is built into the handguard.

 

[CNJarvis]

OTOH, it just occurred to me, that the Remington M700 and clones thereof, have a separate recoil lug that is installed between the barrel and the receiver, similar to the shims on an AR barrel nut, without apparent accuracy issues. Perhaps I'm overthinking this. (as usual)

 

[CNJarvis]

I'm already planning on lapping the receiver face and the receiver to barrel extension fit is good.

I have 3-4 hand guards in mind that do not require the shims but I'm asking the question to broaden my options, especially since I'm trying to keep costs down. ($160 or less)

This will be a hunting and bench rifle so I don't need 6 miles of rails or even keymod or m-lock. The YHM "Smooth" rail is nearly ideal but the longest model is 12.5" and I'd like a 15" handguard.

 

[wxl]

No it should not. Shims should offer alternative to line up barrel nut to line up the gas tube without applying excess torque.

 

[lennyo3034]

Theoretically if the shim isn't of consistent thickness, it can affect accuracy. In reality, the variance in the thickness of the shims is so minute that the effect makes no difference.

I'm running a KAC URX4 of my rifle and it shoots very well.

 

[CNJarvis]

Thanks for all the advice. I decided to go with the 15" Aero Precision "Quantum" handguard. I test fitted the barrel/nut/handguard this evening and it will definitely need the shims. It will be a couple of weeks before I can assemble it but I'll post a pic when I'm done.

 

[JoeBUtah]

Post up pictures of your targets instead....

 

[CNJarvis]

Post up pictures of your targets instead....

That'll be even longer...

 

[Greg Langelius *]

It will make no more difference that changing the recoil lug thickness on a Savage bolt gun (which I have done); effectively, none.

Greg

 

[Pan]

Should not have any effect on accuracy, sometimes shimmy are necessary

 

[CNJarvis]

Ok, so here it is:

<a href="http://s109.photobucket.com/user/cnjarvis/media/849583FB-6817-4C41-B70D-62FA71864025_zpsb1lgz9nm.jpg.html" target="_blank"><img src="http://i109.photobucket.com/albums/n47/cnjarvis/849583FB-6817-4C41-B70D-62FA71864025_zpsb1lgz9nm.jpg" border="0" alt=" photo 849583FB-6817-4C41-B70D-62FA71864025_zpsb1lgz9nm.jpg"></a>

And here's the best group of its initial outing:

<a href="http://s109.photobucket.com/user/cnjarvis/media/C959F715-996C-4A82-B3C6-CDB1BD44E836_zpserbmtsxp.jpg.html" target="_blank"><img src="http://i109.photobucket.com/albums/n47/cnjarvis/C959F715-996C-4A82-B3C6-CDB1BD44E836_zpserbmtsxp.jpg" border="0" alt=" photo C959F715-996C-4A82-B3C6-CDB1BD44E836_zpserbmtsxp.jpg"></a>

Not happy with it, but I haven't done any load workup with it yet. Loads tried were hornady 55 gr. FMJ's over TAC, hornady 55gr. vmax over TAC, Hornady factory "Black Rifle" 75gr. HP, and som 60gr. Federal Fusion that I had laying around.

I only had to torque the barrel to 35 ft lbs with shims to get everything lined up.