Kinda snug is not tight enough for a barrel nut. Torque it between 50 and 80 lbs.
The barrel extension is not "snug"
Although, the barrel nut is not torqued to 50. Its tight, but not 50 lbs. It's about half that...
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Kinda snug is not tight enough for a barrel nut. Torque it between 50 and 80 lbs.
Army trained friend taught me years ago and he cranked them down hard and used anti seize on threads.
25ft-lbs is not anywhere near tight enough. It should be at least 35ft-lbs and usually they end up closer to 50ft-lbs. I've installed a number of barrels and none were ever lined up properly at the low end.The barrel extension is not "snug"
Although, the barrel nut is not torqued to 50. Its tight, but not 50 lbs. It's about half that...
25ft-lbs is not anywhere near tight enough.
Most find the best accuracy when torqued to the lowest value that's higher than 35ft-lbs. If your barrel nut really is torqued only to 25ft-lbs, that's your accuracy problem.
I'm a little confused. If you bought a complete upper, why did you need to loosen the barrel nut? Did you install a hand guard?
OK, now I'm tracking better. Yes, I think the accuracy error is definitely related to the barrel to upper fitment. A new upper is not that expensive so, that's not a bad way to go.I bought a complete upper about a year ago. I was unhappy with the performance. I even sent it back to the company and they replaced the barrel.
I decided to change out the barrel last week. Keep the upper receiver, handguard, bcg, etc and replace the barrel from a more reputable company. Ergo taking the barrel nut off.
When not specified, torque values are for dry applications. However, sometimes they are indeed specified for wet installations. In this case, it's very hard to find the actual spec. I've found lots of youtube videos and articles, but not one actual document specifying torque. But I'm not one to give up so, I finally found one technical manual that had a torque spec in it. Sure enough, it states to apply molybdenum disulfide to the threads. So, yes, the barrel nut and upper threads should be lubed. I stand corrected.vonn said:I think the torque values are based on using lube.
That's a nice rig...
I took it apart this evening. There was a tiny (very minimal) wiggle. I would not describe it as snug.
Something I did notice was the barrel nut. I don't think it was torqued down enough. I couldn't get it tight enough to make it to the next screw hole. I used a shim and it helped me get a bit more torque on it. But I have no faith in that barrel nut and handguard.
I'll take it out this weekend to run a few more 100 yard groups. We'll see...
wylie won wrote:
New Upper on M&P Sport - Accuracy Issue
I put a new barrel on my M&P Sport. I put on a Ballistic Advantage 20" 5.56 DMR Rifle Length AR 15 Barrel, Performance Series.