AR barrel change...

[mrnkc130]

I'm thinking about changing out the barrel on my AR for a slightly longer one, is this just a remove and replace kind of task? Or do the parts wear together and need to stay together? When building a rifle I usually just buy a complete upper, but i was thinking with this next one I would like to buy all the pieces seperate because it looks like it will cost less by the time i replace flash hider and gas blocks and everything else I end up replacing in the long run anyways.

I see the reasoning for keeping bolt and barrel together, but what about barrel and stripped upper? i guess that is my main question...thanks for the help

[roklok]

As long as the parts are in spec you should not have a bit of trouble. I have had numerous barrels on one upper with no problems.

[mrnkc130]

thanks....should i keep the bolt together with the barrel? or is it more important to keep the bolt and upper reciever together?

[DBAR]

I've used different bolts with different barrels. You'll hear people say, that is not the safe thing to do. If the bolt is in good condition, and the head spacing is good, your good to go. You should either have your local gun smith ck head space for you, or you could get some gauges from brownells or Midway.

Bolt and receiver, have no fitting together. The bolt only fits to the barrel extension. The receiver is just a "housing", nothing more. Your complete bolt carrier group just rides through it, back and forth.

DBAR

[Technosavant]

Barrel swaps are pretty simple, but you need some tools: a bench vise, an upper receiver block, a small punch and hammer, a barrel wrench, and a 1/2" drive breaker bar and torque wrench. Some grease will be good too; I use synthetic high temp wheel bearing grease (the Valvoline SynPower stuff, specifically).

Pull the upper off, remove the BCG, charging handle, and handguards. Tap out the pin for the gas tube with hammer and punch, and remove the gas tube. Place upper in vise block and tighten into the vise. Place breaker bar in appropriate spot in barrel wrench, hold the wrench against the barrel nut and loosen (standard threads). Once the nut is removed, the barrel will come right out of the upper. If your new barrel doesn't have the spring, nut, and delta ring, you'll need to pull that off the old barrel (the gas block has to come off for this).

For installation, it is the reverse of removal, but when tightening the barrel nut, put some grease on the threads and use the torque wrench to tighten it to about 35 ft-lbs or so (then loosen/retorque twice), then tighten it to line up the next notch in the nut so the gas tube can be inserted.

As for mating bolts to barrels, you can check headspace with your old bolt- if it passes, you're fine, but if you're putting on a nice barrel, a new bolt isn't that expensive.

[tincanhunter]

^^ Barrel nut torque is 30 lbft IIRC from the military M16 manual. Same installation procedure. 35lbft may make it so that one of the holes in the barrel nut wont line up with the hole in the upper receiver for the gas tube.

[zoomie]

http://www.brownells.com/.aspx/lid=10339/guntechdetail/Changing_An_AR_15_Barrel

[Technosavant]

Barrel nut torque is 30 lbft IIRC from the military M16 manual. Same installation procedure. 35lbft may make it so that one of the holes in the barrel nut wont line up with the hole in the upper receiver for the gas tube.

I've seen people quote anywhere from 30-50+ ft-lbs. Threading on nuts and receivers isn't standardized to the point where a given torque spec will automatically line you up for the gas tube (at least in my experience, maybe some have been working on that, I dunno).

[mrnkc130]

thanks for the replies, another can of worms here...i've seen some headspace gauges that are basically just bullets i think 3 in a pack...i guess you just stick them in there and and if the right one fits you're good. so are they gauging the space in the barrel itself? so if there is too much room or not enough the barrel itself is no good? is that right? can it be repaired? i've never really understood the whole headspace thing or if it is adjustable or repairable....

[mrnkc130]

another question i forgot here...are the chrome lined or nickel lined or whatever they are bolt carriers really worth the money? any recomendations on brands? like i said in OP my next rifle that i plan on building will be from the ground up, if its worth it i'll get one of the coated bolt carriers..

[Technosavant]

are the chrome lined or nickel lined or whatever they are bolt carriers really worth the money?

The only benefit is that they're easier to clean. I don't know that they're really worth 25% more than a non-chromed one from Bravo Company or LMT. I have a couple of Young Manufacturing chromed BCGs, and they work quite well.