I need to tighten the barrel nut on an older upper, but I can't get the gas tube out of the front sight base. The retaining roll pin came out easily, but the tube absolutely will not budge. Are there any tips anyone has, or do I just have to buy that special gas tube removal tool?


Thanks!

I bought the tool and it has come in VERY handy.

looks like I might have to as well....

Just drip a little CLP/Hoppe's in the roll pin hole and were gas tube goes into FSB and let it soak in for a while then grab the gas tube with a pair of pliers or Vice Grips without crushing tube and tap pliers with small hammer to pull tube out of FSB..No need for the $ 25 tool [smoke]

got a bench vise?

Yep. After reading the replies and thinking about it, I soaked the insertion point and roll pin hole in Hoppes and CLP, then put the whole upper in the action block in the vise, then after waiting about 10 minutes, I clamped on the locking pliers, near the base, then wiggled it (rotationally) until it loosened up a bit, then was able to work it out. Completely encrusted with carbon! I was able to remove the barrel, inspect clean, lube, then reinstall. The barrel is nice and tight now, and I have a spare complete upper. Getting the gas tube back on was just as much of a pain, trying to work it back in without bending it, and lining everything back up to reinsert the roll pin. Then of course I dropped the retaining roll pin on the floor and had to get on hands and knees for about 30 minutes, saying some choice expletives and sorting the the dead bugs and dust bunnies on the floor under the workbench. After it was all back together, the function check was good, everything smooth.

All in all, not that bad, but the gas tube was the worst of it. Those are tougher than they look, though, thank goodness.
Thanks for the advice!


here is the maintenance operation in living color

gas tube off

[img]http://www.hunt101.com/img/084084.JPG[/img]

barrel coming off

[img]http://www.hunt101.com/img/084083.JPG[/img]

threads look good

[img]http://www.hunt101.com/img/084085.JPG[/img]

the infamous gas tube

[img]http://www.hunt101.com/img/084086.JPG[/img]


Result: now I have spare, and functional complete upper

[img]http://www.hunt101.com/img/084087.JPG[/img]


or should I build another carbine out of it.....

Yea like anything could get lost in that shop.

Cleaning up ain't one of my hobbies.

You'd be surprised what horrors you can find under the workbench - it was like insect archaeology 101...

Build another carbine bro, you know you want to.

Shabo

Damn, wish I had a shop like that!

Not that hard, I just built the workbench out of 4x4 cedar and marine plywood,attached to wall studs for rigidity. Made the pegboard out of prepainted white pegboards on a 1X2 pine frame again attached to wall studs. The Vise is a columbia 360 degree rotational with built in anvil. nothing too special really. Just got the Peace River action block from Brownells, and ordered the rest of my armorers tools from Bushmaster and Olympic. The cabinets are just typical natural finish kitchen type cabinets w/counter top. I have a lot of tools from when I used to roadrace motorcycles in AMA middleweight supersport class (the sprocket hanging on the pegboard is from my old Honda CBR600F2 that I raced at Daytona in '93 -kind of sentimental).

What can I say, it's my escape from the family, time to myself.

You could pull the FSB and slide it off and tighten the barrel nut then reinstall the FSB with gas tube attached.

Nice setup. What do you use to/how did you headspace the bbl.?

I already got the gas tube off by letting it soak in Hoppes/CLP and working it loose.

Thanks for the suggestion though.

Since this was an upper that had 1000+ rounds through it, and I used the original bolt group for that barrel/receiver, I did not headspace it.

I usually only will headspace a new assembly with an untried bolt/barrel combination. This was just a barrel nut tightening exercise. (made difficult by excessive carbon build-up!)

Do you think I should headspace it before firing it?

_DR,

Next time just invert the upper and clamp the gas tube in the bench vise (that I know see that you have) and pull the tube out of the FSB. Save the pliers and muscle strain.

That would be much easier, rather than popping that vein in my forehead again...

Do you pad it with anything, like a piece of wood on either side, to keep from accidentally tightening too much and flattening the gas tube?

I keep the serrated jaws on the vise and don't clamp down very tight. Never needed any padding. Might have to clamp more firmly if using smooth jaws.

My vise jaws are serrated. Thanks, I'll try that next time.