Barrel Shims

[DRAM40A1]

I mounted a Ballistic Advantage 308 barrel on a Mega Maten receiver set this morning and properly torqued it to 60 pounds after tightening and loosening a few times but noticed that the Centurion CMR barrel nut jambed against the receiver face while I was tightening it down. I was checking the stiffness of the handguard to make sure the rail wasn’t contacting the gas block and noticed the barrel is actually slightly loose. I suppose I’m going to have to use shins behind the barrel nut or should I have some material removed from the barrel nut where it is contacting the receiver?

 

[Spblademaker]

Just get the shims. Also is that gas tube free to move around where it enters the upper?

 

[DRAM40A1]

It’s also contacting the barrel nut, therefor not free to move around. The barrel nut is pushing it upwards. What’s the fix? Bending the tube?

 

[Spblademaker]

I wouldn’t mess with the tube, but that’s me. Never ran into either of those issues before. Also never used the Centurion handguard. ?

 

[DRAM40A1]

The original barrel nut wouldn’t go over the barrel extension and this is a replacement from Centurion. So, this one sucks too? LOL

 

[Yondering]

I hate to say it, but I'd be looking for a different handguard entirely because of those barrel nut issues. That gas tube should be free to move, and the barrel nut absolutely should not contact the front of the receiver like that. There's really no excuse for a poor design like that in today's AR15 market.

 

[clcustom1911]

Geissele and don't look back

 

[bigjake83]

There are plenty of decent handguard options just make sure to bring your lube for your asshole or your wallet.

Take a look on Rainier Arms see what they have available also SLR has some good stuff as well.

I would also further inspect your upper receiver to make sure no damage was done while the barrel nut was torqued against the receiver face.

It really looks like you've got a mixed matched bag of kit here, I'd say stick with the mega receiver set, and possibly reevaluate your barrel and handguard situation. Did you buy the barrel and handguard new or used???there are definitely some compatibility issues here.

 

[bfoosh006]

Lot of good points in this thread... you do not want the gas tube being a "force" in any way.

You need consistent / easy return to the same BCG locked position... a contorted gas tube will not help at all.

You could bend the gas tube , gently... they bend / kink easily.

As for the barrel nut contact at the upper's face...( has to be fixed ) and dependent on your OCD... mine is pretty bad, Lol...

I would probably sand some of the ass end off of it.

I even did it to my Lancer Carbon Fiber FF tube mounting nut.... function over cosmetics.

Or if that doesn't work for you... send it back.

BTW... is that barrel nut steel ?

 

[DRAM40A1]

I originally built the Mega with a 12.5” Bartlein from Craddock as a pistol. I bought this Centurion CMR deeply discounted from Rainier. The original barrel nut would not slip past the barrel extension so I called Centurion and they sent the replacement, which is larger in diameter, which caused the interference with the gas tube.
I really did not like the arm brace used to make it a pistol so just as a cheap alternative, I bought the Ballistic Advantage 16” barrel, again at a discount just to play around with. I’ve sent two emails to Paul at Craddock that went unanswered about making me a 16” fluted Bartlein barrel. I guess I’ll start calling now. LOL

I have SLR, JP, and Badger Ordnance on other large frame ARs.

PS, I built it again last night on a new Aero upper because the original barrel nut actually fit over the BA barrel. The gas tube issue is no more but it still slightly makes contact with the receiver. ?

 

[DRAM40A1]

I think I’m going to remove a little material off of the front of the nut to relieve the contact and roll with it.
And yes, it’s steel.

 

[DRAM40A1]

Here it is as a 12.5” Bartlein barreled “pistol”.

 

[DRAM40A1]

Just an update. After removing material from the front of the barrel nut and relieving material that was binding the gas tube, I dumped the CMR and installed this 16” SLR Solo Light. I bought it used on Barf.com for $130 shipped. It’s a little too long but that Lantac Dragon is still forward of the rail.

 

[Yondering]

It looks good.

No more fit issues?

 

[DRAM40A1]

It looks good.

No more fit issues?

Correct, no more fit issues.

 

[DRAM40A1]

I just can’t leave well enough alone. I ran across this 15” Noveske N6 rail and well, I had to do it!