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Discussion Starter · #1 ·
I got time to shoot my tac yesterday after it's 2nd time back to S&W for short stroking 5.56. I have to admit I was pissed when I tried the 5.565 thru it again and got double feeds and some short strokes.

The short stroke 5.56 issue was what I sent it back for the 1st time (not fixed) and the 2nd time. On the 2nd return they replaced the barrel. Took it to the range yesterday, after I had short strokes and double feeds (a new problem), I took it apart and gave it a good cleaning this morning. I was shocked at all the carbon, oil and gunk in it. Al and his guys must have shot the piss out of it after the barrel replacement.

Anyway, after I cleaned it and lubed it, off to the range I went. NO problems encountered. I will have to shoot this rifle alot of problem free times before I can ever trust it after all the problems I've had with it.


Like a poster in the old thread said, I was told the barrel nut on the original barrel was "finger tight" on the original barrel, and it had wore a hole in the gas tube also as a result. My rifle is one of the 1st made for S&W by Stag. Makes me wonder about the Stag quality. The first time I ever took the rifle apart for pre-shooting lube, I was amazed at how clean it was. It appeared to have never been fired at all.


Site Staff
9,636 Posts
Don't sweat the carbon, that's normal and you SHOULD NOT attempt to scrape it off, leave it alone it will take care of itself.

Ignoring Carbon Build-up - per Armalite

There are frequent posts asking about cleaning carbon from the AR. We've decided to post our answer as a separate topic for your reading amusement:

Hold off on removing the carbon. Leave it.

Now that we've got your attention, we'll explain.

Deep inside the AR-10 or AR-15/M-16 bolt carrier is a groove at the end of the chromed cylinder that the gas rings slide in. That groove is GRIND RELIEF. It's a production artifact. It prevents a ledge from being left where the grinding for that cylinder ends.

Carbon can build up in the groove and the rear surface of the carrier. It is harmless. The high pressure/temperature operating gas keeps it from building up too much. About the time it gets too bulky, it gets blown out.

Don't confuse instincts for cleanliness that you learned in the military with common sense. It's easy for an inspector to know when there isn't a speck of dirt. It's harder to know what's important.

Any scraper that'll get to it can damage the ground surface inside the carrier. Bad deal.

Clean out what you can with patches or Q-tips, but white-glove cleaning damages more guns than all the shooting we do.

298 Posts
I was the guy (Robb/gotm4) that repaired Tang419s S&W. It works now.

CMT/S&W did many things badly:

My findings so far:

1.) The gas key was leaking. It wasn't loose by feel but upon removal I did find oil between it and the carrier with evidence of carbon tracking (from gas leaking around the front of the key). I installed a new carrier key and screws.

2.) I removed the barrel from the upper receiver and found that the barrel nut was on with about 10ft lbs of torque and not aligned well at all. The barrel was so loose that it allowed the barrel to turn laterally in the upper receiver with moderate force and the gas tube was canted inside the upper receiver. I reinstalled the barrel which required roughly 60ft lbs to get good barrel nut/gas tube/receiver alignment.

3.) The chamber wasn't a true 5.56mm (I'm always suspect of this of all barrels except for Colt). I remedied this using w/Ned's 5.56mm NATO neck and throat reamer.


I don't think the S&W (CMT/Stag) is made using 'cheap' parts. IMO this S&W was just poorly assembled from the factory.
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