A2 does not cycle

[esaabye]

I have an bushy A2 20inch Hbar and it is no longer cycling correctly. Today it ran fine for 30 rounds then slowly turned into a bolt action rifle. The bolt would catch 3/4 back then not at all. Same load I normally shoot and that shot fine from a 16inch today so I think it is the rifle.

Where do I start looking for the problem?

I cleaned it tonight, dripped some clp down the gas tube and it drained fine.

[GunTroll]

I have an bushy A2 20inch Hbar and it is no longer cycling correctly. Today it ran fine for 30 rounds then slowly turned into a bolt action rifle. The bolt would catch 3/4 back then not at all. Same load I normally shoot and that shot fine from a 16inch today so I think it is the rifle.

Where do I start looking for the problem?

I cleaned it tonight, dripped some clp down the gas tube and it drained fine.

You and me both guy!

[esaabye]

You and me both guy!

You inspired me.

Just a strange thing, worked fine for 1st several thousand rounds but now, bolt action.

Think I must have plugged up the gas port or the tube but not wanting to take it apart yet.

[Backinblackrifles]

I have never seen a clogged tube or port to much pressure. I don't advise sticking anything down it either You probably wont get it back. Check for binding of the carier and gas tube by stripping the bolt carier and runing it up and down by hand listen and feel for any binding. I would bet this is the problem aspecialy if it works well the first mag or so it is fouling and binding. Clean the gas/carier key out realy well soak it over night in brake cleaner then scrape out the carbon fouling wich is usually hard as a rock from being baked in. Also no ball powder or laquered cases.

[spencerhenry]

bushy with bushy mags? i have seen several bushmasters that with factory supplied mags are unreliable. try some other mags, that fixed the problem with the ones i am familiar with.

[Hoser]

Gas issue.

Check your front sight for leaks.

Maybe it needs some oil..

[esaabye]

Gas issue.

Check your front sight for leaks.

Maybe it needs some oil..

So I torn it down after talking with the guys at Bowers and reading the suggestions on here. Could not find a problem, gas tube is clean, gas rings are good and hold, everything lines up.

I was putting it back together when I rememberd that I had modified the charging handle by sealing the gas port so I would not get blowback. I am hoping this was the cause of the poblem, by not allowing the release of the spent gas out the rear it could act like a compression break and slow the bolt.

We shall see Saturday.

[Quib]

I recently did a write-up on AR15 troubleshooting, with a list of probable causes.

Maybe it can get you headed in the right direction....

http://http://www.weaponevolution.com/forum/showthread.php?2442-Principles-Of-Troubleshooting-And-The-AR15

[BPTactical]

I think we are overlooking something very simple here.
Sounds like possibly a gas key has started to loosen. Clean your bolt carrier/key well with some BrakeCleen or similar and allow it to dry. Take one drop of solvent and carefully place said drop in the gas key and allow it to run into the bolt carrier. Examine the joint of the gas key/bolt carrier carefully. If you see ANY evidence (wet) of leaking at the joint then you must have the key lapped and reinstalled.
You can check your gas block the same way.
With the bolt sticking @3/4 it sounds as if it is short-stroking.

One other thing to check-Make sure that the hole on the upper stock screw is not plugged/blocked in any way. If it is you will get a short-stroke because of the retardation of the buffer traveling. All it takes is slowing it down by milliseconds to throw the entire timing cycle off...

If you are still stumped shoot me a PM.
Good info Quib.......

[Quib]

Good info Quib.......

Thanks. It's a constant work in progress.

If anyone has something to add to the list, please let me know. I'm in the process right now, of converting the text into TS Charts.