Oddly specific AR bolt question

[knox]

So I built an AR. My bolt is an ares. When my bolt is in my gun, the gun will fire but is extremely tight when trying to mate/unmate it with the barrel and will not extract or eject the casing.

Used my friends PMS BCG and it still had the same symptoms except now it mated with the barrel the way it should.

Both BCG operate perfectly normal in my buddies AR.

From what I read I can not adjust head spacing on my barrel. The only thing I can think of would be my gas tube leaking. But this would only fix my eject/extracting issue.

So in the end, What could cause my BCG to be extremely tight in my gun, but work in others?

 

[robert]

Barrel out of spec would be my first thought. Headspace is adjustable, just very rarely needed. Gas tube is only going to effect speed with which the bolt moves, check the carrier key on the bolt carrier and make sure it is secure and staked and that the tube isn't getting jammed down in it. I've seen one where a guy put the gas tube in with the pin in front instead of through the hole so the tube was projecting into the receiver too far. It shouldn't go into battery that way but you never know. The gas port on the gas tube is facing the correct direction right?

Depending on how much it's been shot, pull the bolt out if the carrier and inspect for carbon buildup. Inspect the rings to make sure they are in good shape and gapped properly. Tap the pin out that holds the extractor in place and inspect and clean it, replace the spring.

The buffer detent isn't rubbing the carrier and you buffer tube is in good shape?

 

[cjl1357]

Chamber or barrel is out of spec for 5.56

 

[Ol_shamus]

x2 on headspace. Take it to a competent gunsmith, and they will likely be able to figure it out for you relatively quick. If your're a DIY type, you can buy a headspace gauge from places like midway usa.

 

[11b4v]

Head space Is Not adjustable on an AR barrel. Once the barrel extension/head space is set, the barrel extension (chamber lugs and feed ramps) is pinned to the barrel, its pretty much done. Removing the barrel extension pin, then head spacing and drilling/reinstalling the barrel extension pin is pretty much unheard of since you'd be drilling a hole just a hair over/past the previous drilled hole. If its of spec, toss it, install another barrel.

Rule of thumb. Used barrel and new bolt; used bolt and new barrel; new bolt and new barrel; Never mate a used barrel used bolt.

Borrow AR head space GO/NO GO gauges for find a local Smith who will gauge it; should be cheap fee wise.

Do this first. Take an AR bore brush (large dia. stainless bristles mated to the smaller dia., brass bristles) insert it into a single section of cleaning rod, put it in your drill, and spin the hell out of your chamber.

And keep using that cheap, Russian lacquered, steel case crap if you want to foul you gas tube, burn out our barrel faster, gum up your chamber, and wear out your extractor.

If if doesn't fix it. I'd just toss/return the barrel for a replacement.

Gas tubes only "leak" when the bell at the end of the tube is worn excessively/End of Life. A properly staked gas key/carrier will leak of their mating surfaces arent true. Most likely to occur on budget parts.

AR15.com and M4carbine.net are your friends here.