Is this a problem? If so, please help!!

[pdc]

Gents. I think I have a problem but am not sure what it is. I was tinkering with my Mega MA-10 build last night and installing a new low profile gas block. I noticed that it seemed like the barrel was moving so I investigated further. Sure enough, when you grab the barrel and do a twisting motion there is almost imperceptible movement. You can't really see it but you can feel it. There is no front to back movement though. The barrel is a *See Site News* Weaponery and the barrel nut is a Troy for my TRX-308 handguard. The nut was torqued at about 35lb pounds. Troy specs call for 30-50. What is causing this? It's not a good thing right? I have fired only about 20-30 rounds through this rifle so far.  Please help.

[RayGun19]

Sounds to me like your barrel nut has loosened. If the build isn't that old, it may just need retorqued. Aluminum threads can stretch slightly on initial torque on almost any aluminum assembly.  That may be why Troy called for 50lbs.

[pdc]

I'm going to torque it some more this weekend.  Thanks for the advice.

[imschur]

Interesting. Did the barrel extension look correct?

[JMoto]

Sounds to me like your barrel nut has loosened. If the build isn't that old, it may just need retorqued. Aluminum threads can stretch slightly on initial torque on almost any aluminum assembly.  That may be why Troy called for 50lbs.

When installing a barrel I always tq to min. spec and then loosen, and repeat a couple of times and then tq to min spec again and then tighten until the barrel nut aligns with the gas tube hole, I usually do not run into the described issue this way.

[98Z5V]

Sounds to me like your barrel nut has loosened. If the build isn't that old, it may just need retorqued. Aluminum threads can stretch slightly on initial torque on almost any aluminum assembly.  That may be why Troy called for 50lbs.

I don't think that's the case here at all.  The index pin in the barrel extension fits into a pretty tight groove in the upper.  Unless that groove is damaged (widened), or the pin is damaged, even with a loose barrel nut that barrel won't rotate like the OP is saying.  It just won't happen with a loose barrel nut.

Now, a barrel extension that wasn't torqued properly when the barrel was built...  that's another story, and it is probably what happened here.  The actual barrel extension has the barrel index pin in it - that part is in the upper and the slot.  If the extension is loose, the barrel can turn.

With that barrel nut put on there at 35lb/ft, the barrel nut isn't loose.

[pdc]

The barrel/extension looked fire prior to install.  I think the extension is moving as well.  I'll try to wiggle it while looking at it from the inside of the receiver.  That will tell me if even the extension is moving.  Will update later.

[pdc]

Problem solved!!!  Just needed to be torqued a bit.  When the smith went to pull the barrel the nut came off with little more force than the weight of the wrench.  It's not going anywhere now.  Thanks guys.

[survivalshop]

Problem solved!!!  Just needed to be torqued a bit.  When the smith went to pull the barrel the nut came off with little more force than the weight of the wrench.  It's not going anywhere now.  Thanks guys.

Ummm ?