AR15 ? not chambering second round

[randyrat]

Friend of mine called and ask me to solve a problem with an AR15 Bushy 223..

He called and said it would not chamber the second round.

He would place a mag in and hit the bolt release chambering the first round, fire and eject the first round, but would slide over the second round. MMMMmm i thought maybe a mag problem , bent lips? wore/ week spring.

He did try two different mags, with the same results. ( He also said it is not very old/ used)

I've cleaned a few Ar 15s for a few buddies and showed how to field strip them, but i haven't shot one of these in 30 years.. Any ideas out there? Where do i begin?

I don't have the weapon in front of me until tomorrow, my friend plans on dropping off the problem child.

[GabbyM]

what ammo is he using. since this sounds like a short stroke.

when you take a look it may be obvious. I had an AR once where the previous owner thought motor oil down the bolt carrier vent holes was a good thing. It was locked up solid with carbon. Took a few days to decarbon it.

[c3d4b2]

One guess is the bolt is not cycling back far enough.

Is there a gas leak where the gas tube connects to the front site?

Does the gas tube and the bolt carrier key line up correctly?

What model Bushmaster does he have? Could he have a standard buffer spring in a carbine length?

What load is he using?

I would recommend he call Bushmaster.

[Jon]

sounds like a shortstroke to me as well if it's not a magazine problem. Is he using milspec mags?
The cheapie steel mags always gave me trouble. If the magazine is nice and tight then it's probably ok.

Make sure you clean out the gas system, and check for too much grease or oil in the buffer spring.

[mike in co]

how about asking what he has done diff since the last time it did cycle properly ?

why look for something that aint broke ??

find out what changed......


mike in co

[WILCO]

I would recommend he call Bushmaster.

Ditto for me.

[Johnch]

I had the same problem years ago with some NEW Colt 10 rnd mags
Turned out it was the mag spring

Replaced the spring and no more problems

Called Colt and was told they don't warrenty mags
Sold the rifle

Last Colt that will ever be in my house

John

[imashooter2]

Since he had the issue with 2 different mags, my money is on the short stroke. Is he using quality factory ammo? I've had fast powder reloads that wouldn't cycle the gun until I was right up at max. A simple test is to load one in the mag, chamber, fire and see if the bolt locks back.

[captainkirk]

The gas key could be loose/not properly staked and it would give you this result. Mag problems, and ammo not hot enough addressed by other posters are also definite possibilities.

captainkirk

AR15.com is full of info as well, but I think the problem has probably already been listed with the folks above.

[dk17hmr]

We have had a problem like this with a few AR-15's. Most of the time, when using known good ammo, there was a leak around the gas block. Used some Green LockTite, the penetrating type, around the handgaurd side of the block and the problems went away.

A leak there would be obvious on the barrel where gas was coming out.

[clodhopper]

I have had that problem when the gas rings were worn out.
Did your freind buy the rifle new or buy from some one who "just shot a couple of boxes of ammo"?
How big was that box of ammo?

[randyrat]

My friend just bought the gun used... All these replies are cleaning out the cob webs in my brain and are making sense now.
I haven't looked at it yet, but from what i've been told here and what i'm familar with i'll bet someone just soaked the heck out of it with grease or oil and plugged something up.
Thanks......Now i have a place to start when he brings the rifle over. I'll call my friend and have him bring me some pipe cleaners along with the rifle.

[imashooter2]

I've never heard of a gas tube plugged by anything except pipe cleaners...

[mooman76]

You said he tried two magazines but were they two of the same type. I never understood cheap mags when someone told he he was picky about the mags he bought until I bought a couple. I could bend the tabs with my fingers. There are allot of cheap mags out there and it's funny how some people will spend a small fortune on a good gun but buy the cheapest mags or ammo they can find. I now know why too when I go shooting I always see mags that were shot up and laying on the ground.

[randyrat]

I've never heard of a gas tube plugged by anything except pipe cleaners...

That was the idea... So he dosen't try to plug the gas tube up with them.

[longhorn47]

You got a leak

[randyrat]

My friend dropped off the rifle and i field stripped it and looked under the hand guards, no leak that i could tell. The rifle looks like new. I gave him a name of a gun smith that knows more about these rifles, he also has a stash of good mags he can try and eliminate that possibility.
I'll post when i find out what is causing the trouble.

[StarMetal]

My friend dropped off the rifle and i field stripped it and looked under the hand guards, no leak that i could tell. The rifle looks like new. I gave him a name of a gun smith that knows more about these rifles, he also has a stash of good mags he can try and eliminate that possibility.
I'll post when i find out what is causing the trouble.

Chamber a factory round and put an empty magazine in the rifle and fire it. If it doesn't lock back look for the reasons that cause that. I highly doubt it's the magazine, but you never know, it wouldn't hurt to try the same test with one. While you have the rifle hinged open try the bolt/carrier group by hand and see how easy it slides and the bolt locks into battery. If it does try the same thing by hand slowly with the rifle hinged closed and a magazine in it. The gas tube on an AR can't be too far out of alignment because it won't slide through the barrel nut went assembling the rifle. It's possible it could be bent after it's been assembled, but let me tell you they are stout tubes. Try drilling a hole in one sometime. I make adjustable gas valves for them and they require a premium drill bit. What can happen is during assembly is the barrel can be a hair of being straight up and down in the receiver. In other words the feed ramps should be a the exact 6 o'clock position may not be and the bolt has resistance going in and out of the barrel extension. Thanks to the AR's sloppy tolerances in that area it can achieve this if it's not real far out of alignment. Don't believe the myth about misaligning the gaps in the gas rings, but it's nice to scramble up some when you assemble the bolt. If the rifle has only digested factory ammo I highly doubt anything in the gas system is plugged up. I've fired my AR's with some really really anemic cast loads and was surprised they functioned the action fully. Not likely, but if the front sight isn't exacty in the 12 o'clock position the gas port could be partly blocked off.

There was a statement about globbing lots of oil on the bolt causing it to gum or plug up. Probably true with many oils, but I know a large group of AR/M16 enthusiasts that swear by light grade of Mobil 1 synthetic oil. I've used this oil a lot myself and with no problems.

Keep us informed.

Joe

[dpaqu]

I have the same problem with my bushmaster carbine firing American eagle’s tactical XM193 cheap ammo. Not always the second shot but sometimes it does shortstroke. It happened less when I switched from the 5 round mag to the 30 rounders but it still happened.

I got the gun in January from a friend who lost his job as a machinist. He said that it worked for him. He also had gave me one of these

Which I installed before I went to the range. I will be going to the range again in the near future. I will try the gun with and without the fancy buffer and with what I have left of the xm193 stuff. I also got 200 primers from a local gunshop that is rationing them. I reloaded the XM193 brass with 28gr of H335 and 40gr moly coated v-max bullets because they were the only ones on the shelf. Hopefully they cycle the action and hopefully they don't fly apart on a 9 twist barrel.

[Storydude]

Bushcrapster shortstroking problems in order:
Loose/improperly staked gas key
Improper size gas port in barrel
Wrong Buffer