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lengthofpull
10-23-12, 23:32
A friend asked me this question and I had no idea, so I figured I'd ask the folks here.

Do all styles if barrel nuts, assuming they are all torqued to spec, have any impact on the mechanical accuracy of the gun? I.E. if you had a complete gun (with standard barrel nut) that shot 1 MOA, would accuracy change depending if you had it with a DD barrel nut for a lite rail or KAC barrel nut for a URX 3.1? Or would the gun shoot exactly the same?

I am guessing that the change, if any, would not be perceptible for 99.9% shooters out there. What do you think?

-LOP

lwrkeysfisher
10-24-12, 05:59
I spoke to Wes at MSTN about this while trying to choose a hand guard for a recent build. Wes stated that there was no difference amongst top quality hand guards (PRI, KAC, Noveske, & DD) as long as the barrel nut was properly torqued.

He's built a bunch of fine rifles for me, so I trust his opinion.

ICANHITHIMMAN
10-24-12, 06:46
Good question, interesting I have wondered this from time to time. If accuracy is no affected I wonder which is stronger.... No I have to think about that all day, darn :cray:

ALCOAR
10-24-12, 08:45
The barrel nut for an AR-15 plays a key role in the overall accuracy/precision of it for sure. It affects the accuracy in several critical aspects....

1.) Harmonics, rigidity, and the amount of barrel whip are all effected by the barrel nut's design.

That would be the aspects of accuracy that are effected by the barrel nut.

2.) Heat dissipation ability, more specifically the ability to dissipate heat from the chamber, and the barrel overall is critical to maintaining precision with a rifle. A poor barrel nut design will be terrible at dissipating the heat being generated from firing, thus making your rifle's POI wander much sooner due to the excessive, prolonged barrel temps.

This would be the aspect of precision being affected by a given barrel nut's design.

The reason I'm first and foremost a believer in the MRP/MWS monolithic chassis for my precision based ARs is because of the way in which it mates the barrel extension within the chassis, thereby all together killing the actual barrel nut design, and providing the barrel with a single continuous/monolithic chassis in which there is no separation of parts (i.e. barrel nut / barrel / upper rec. / rail VS. barrel / monolithic chassis ) in which to lose the abilities to dissipate heat off the barrel/chamber.

If you can maintain your barrel's natural harmonics (reducing all excessive barrel movements associated with firing, and then adequately keep excessive barrel temps from building up....your gonna have an inherently accurate rifle.

Outside of a LMT mono chassis, the Geissele SMR barrel nut design would be my runner up in terms of significantly improving the barrel nut design over a traditional one with respect to seeking high levels of accuracy/precision. It provides lots of surface area that mates into the FF rail, thereby providing significant improvements in heat dissipation. I also personally believe the beefier barrel nut on the SMR leads to an overall more rigid complete upper receiver, and again reducing excessive barrel movements, or barrel "whip" during firing.

Lastly, just to clarify...the reply above is speaking in the context of true accuracy/precision VS. AR GD where generally anything beyond combat accuracy 2-3moa is not needed nor measured that closely.

lwrkeysfisher
10-24-12, 10:16
I think it is important to differentiate between monolithic/pseudo-monolithic designs and other designs where the barrel nut is also the coupler for the the Handguard. I think monolithic designs are likely more accurate; however, I would need to see empirical research to be convinced that the difference is significant. I've owned both types of uppers, and have found that the barrel and feed-ramps play the biggest role in accuracy, not the hand guard.

ALCOAR
10-24-12, 11:20
I think I agree with you....

Besides providing a better platform in which to mount powered optics, and overall increasing the durability, or strength of the complete upper receiver, "monolithic ARs" or "polylithic ARs" (Vltor VIS/Mega mono uppers/Colt 6940 SP901) do very little if anything over any of the current high quality traditional barrel nut designed rails like the offerings from KAC, DD, Troy, Centurion, Noveske, etc.

Ultimately they can't escape the barrel nut design either, and like you mentioned they still use a barrel nut design thereby creating 3 major separations on the upper receiver group..the barrel / barrel nut / monolithic chassis or polylithic chassis.

The MRP/MWS isn't really even comparable to anything else which includes any of the monolithic offerings from others.

Just to reiterate from above, the most important feature to the MRP/MWS for myself is the one of a kind barrel hookup within the chassis, or essentially the fact that it doesn't use a barrel nut, and the entire barreled upper consists of only a barrel and chassis.

eta


On the MWS, it's much easier to see what I'm talking about....the MRP/MWS design captures more of the barrel extension, and mates it directly into the one piece chassis. The end sum is that a significant amount more of the barrel extension, and then the actual chassis is being mated together thus increasing heat dissipation, reducing the amount of barrel flexing, and lastly adding more overall rigidity into your upper receiver group over a normal barrel nut design/FF rail/barrel.

http://i888.photobucket.com/albums/ac81/trident1982/DSC03606-1.jpg

JohnnyC
10-24-12, 13:29
I feel like if you're so concerned about the minute degree of accuracy you might gain by swapping barrel nuts then you're gaming in a shooting sport where using an AR is the wrong tool to be using to begin with.

Obviously a way out-of-spec barrel nut might trash your accuracy, but that's just as possible with an out-of-spec barrel nut by any manufacturer.

As far as the MRP/MWS barrel system is concerned, accuracy by way of lack of a barrel nut is so far outweighed by other benefits of the system that I don't even think it would be a viable quality to even test for.

Unless you've got a completely fubar'd barrel nut, I think it's probably sucked so far down in the minutia that it's not even worth considering. I would never choose a rail based on the type of barrel nut for example, as the rail itself would play a far greater part in addressing my needs than the attachment method it uses.

Trident has already covered the benefits of the MRP/MWS system, and they are vast. I think if you're concerned to the point where you're sketching out over a barrel nut, you should just go with the MRP.

ALCOAR
10-24-12, 14:05
On second thought, I have no interest in having this internet discussion....even though I would like to be a dick.