AR fails to feed off the magazine

[magnum12pm]

I won a Bushmaster XM15 in a gun raffle. I have fired 350 rounds through it so far. I have never owned a rifle before, so I am lost. When I chamber a round and fire sometimes the action cycles but the bolt fails to chamber another round from the magazine, so I have an empty chamber. I manually rack the charge handle and its fine. This seems to happen 2 or 3 times out 10 shots. My cousin says the magazine in defective in some way. What do you guys recommend? I am a handgun guy, don't have a clue on AR 15.

 

[zercool]

How thoroughly have you cleaned and lubed? What ammo?

The AR gas system may be slightly clogged or the front sight base/gas block may be canted just enough to partly obstruct the gas port. A tiny under-charge in a cartridge would prevent the bolt from fully cycling.

I would definitely find a couple more magazines and try those as a first bet, though. Check out 44mag.com for some decent prices. Different ammo would be my next bet, unless you're already shooting known quality ammo (Fed XM193, Hornady TAP, etc).

If all else fails, slide over to ar15.com and ask for some advice. You'll get some flak, but there are also a lot of guys over there who know ARs inside-out and can point you to some more things.

 

[Joni_Lynn]

It sounds like the bolt isn't traveling far enough back to pick up a round. It's sort of short stroking. Clean and lube the gun, check the gas tube and gas key to see that they are in the right place and in good shape. The gas block may have been moved slightly or be a little loose or the gas tube could be full of crud or damaged.

Good luck.

 

[magnum12pm]

Thanks for the input, I have cleaned it well. I was over to AR15.com. They have some posts about how to check for short stroking and what to check. I'm a hand gun guy and feel like a 3 year old with this weapon. I will try some of their suggestions and tests next time I get out to the range. I was at Vandalia Amory and range in Dayton, Oh over the week end. They have a 100 yd. indoor range there. Its quite a setup. The shooter has a computer screen right next to you. It shows where your shot hit on the target and the middle of your group. It showed I was shooting 9/10 on an inch groups. I think I will be satisfied with that in the accuracy department, when it becomes more reliable.

 

[SW CQB 45]

if your gas key is loose, gas could be escaping out causing short strokes.

check your carrier and look for evidence of carbon or gas residue escaping out between the gas key and carrier.

it is tighten down with cap screws. a temp fix is clean and red loctite. the body of the gas key should have been crimped over the screws to prevent backing out, unless someone has messed with.

was this gun used?

 

[magnum12pm]

if your gas key is loose, gas could be escaping out causing short strokes.

check your carrier and look for evidence of carbon or gas residue escaping out between the gas key and carrier.

was this gun used?

No this was a new gun, I have shot about 300 rounds since I have had it, about six months. I will recheck everthing next time I get a chance to take it out.

 

[SW CQB 45]

another area to check is the gas rings which are inside the carrier and around the bolt.

if they were not lubed when new, they might not have broken in correctly.

dont use rem oil on an AR. it has the consistency of water and will wear off very easily.

one way to check if you rings are ok, remove the carrier assembly, and have the bolt extended. set the carrier on the table, bolt down. if the carrier does not move down, your rings have sufficient tension/seal. if the carrier moves down, the rings might not be seated well to the walls of the carrier.

if you were close to Victoria, TX, I could check out your piece.

I am over the armory in our dept.

 

[magnum12pm]

another area to check is the gas rings which are inside the carrier and around the bolt.

if they were not lubed when new, they might not have broken in correctly.

don't use rem oil on an AR. it has the consistency of water and will wear off very easily.

one way to check if you rings are OK, remove the carrier assembly, and have the bolt extended. set the carrier on the table, bolt down. if the carrier does not move down, your rings have sufficient tension/seal. if the carrier moves down, the rings might not be seated well to the walls of the carrier.

if you were close to Victoria, TX, I could check out your piece.

I am over the armory in our dept.

Well thanks for the offer. I was proud of my self for being able to reassemble the weapon the first time I took it down to clean it. I take care of my hand guns easily, but I wasn't sure about an AR. Its amazing what a simple task it is to tear down one of these weapons. I guess it makes since since our armed forces have to do it in the field.

 

[SW CQB 45]

Read the first poster on this link.

it give many areas to check.

http://m4carbine.net/showthread.php?t=138

 

[Hangerbanger]

You might want to take a look at your buffer spring. The buffer spring is in the buttstock and is what stops rearward bolt travel. It also returns the bolt to battery. I had a similer problem with a gun built from a parts kit. The spring supplied with the kit was too long and did not allow the bolt carrier to cycle correctly. Also there is a small hole in the screw that attaches the butt stock to the buffer tube the purpose of which is to let air escape as the spring travels reaward. It may be possible that the hole has become clogged with foreign matter and is not relieving pressure when the bolt is moving rearward. Good luck.
Barry

 

[BruceM]

Interesting thread but doesn't this belong in the Gunsmithing Forum or the Lounge?



Bruce

 

[jcall]

Interesting thread but doesn't this belong in the Gunsmithing Forum or the Lounge?



Bruce

The OP is having an issue with his "long gun". why would you put it anywhere else??

I had a couple of similiar issues with my M&P15 and more lube was the answer. these rifles love to run wet. Good luck and have fun with your new rifle.

 

[BruceM]

"The OP is having an issue with his "long gun". why would you put it anywhere else??"

Well, because the name of this Forum is S&W Long Guns just as the above Forums are named S&W Autoloaders, S&W Revolvers, etc.. It is not named "Long Gun". Is this a Smith & Wesson long gun? If this is an appropriated location for this thread, them the discussion of any brand of revolver or autoloader would be similarly appropriate for the above Forums. This, obviously, is not the case. It's not a matter of whether this is a suitable subject because it is. The thread is just located in the wrong Forum.

Bruce

 

[Bob R]

Do you only have the one magazine for it? If so, go get a new one and try it before you go tearing into the gun.

Clean, lube, try a new magazine and see how it works.

If it does it with every magazine, then go looking for other causes.

bob

 

[Jolly]

You might want to take a look at your buffer spring. The buffer spring is in the buttstock and is what stops rearward bolt travel. It also returns the bolt to battery. I had a similer problem with a gun built from a parts kit. The spring supplied with the kit was too long and did not allow the bolt carrier to cycle correctly. Also there is a small hole in the screw that attaches the butt stock to the buffer tube the purpose of which is to let air escape as the spring travels reaward. It may be possible that the hole has become clogged with foreign matter and is not relieving pressure when the bolt is moving rearward. Good luck.
Barry

That hole is a drain hole and not a vent hole. I put a 1" stock extension on my Bushmaster and the longer screw had no hole. Functions fine without it.

 

[magnum12pm]

Interesting thread but doesn't this belong in the Gunsmithing Forum or the Lounge?



Bruce

You are most likely right Bruce, I screwed up, not much I can do about it now! If it were moved to the appropriate spot that would be fine. I will try and do things properly in the future. I thank everyone for their ideals, that gives me plenty of things to check out. I don't think it is any thing serious as this was a brand new weapon. I just needed some hints on where to look, since I have no experience with ARs.

 

[84CJ]

One other thing to check. Make sure the gas rings are staggered. As things get worn this becomes more of an issue.

 

[tom turner]

Hi,

Also, you didn't mention the kind of ammunition you were running when the gun choked.

If it's ammo-related, it would probably be some of the low-cost steel case stuff such as the Wolf ammo. Lots of it is out-of-spec.

I recommend breaking in any AR for about 300 rounds of brass cartridge ammo from a reputable American maker. Once you've run that amount through the gun, if those other potential issues are not present, your Bushy should digest about anything you want to put in it, and sling the empties out like goose crap.

The "economical" Wal-Mart boxes of Federal .223 FMJ are a very good choice and you can count of 'em to be in spec and to help break in the cycling of the AR just right.

T.


BTW . . . always use lubrication when shooting an AR. Those suckers like it slick!

 

[m1gunner]

Get a bottle pf liquid CLP, Midway has a 16 os squirt bottle for about 15 bucks. You need this stuff if you own an AR.

Take the bolt assy out and break it down. Clean it well including the firing pin channel and the gas chamber under the key. Put 2 drops of CLP on the gas rings before you put the bolt back in the carrier.

Reassemble everything and do not forget the cam pin (NEVER forget the cam pin unless you want the bolt installed in your cheek),

Before you install the bolt carrier assy in the upper, wipe the upper out and remove carbon, powder, dirt, etc. Then put 2 drops of clp on each slide surface on the carrier (there are 4 raised and polished ribs that ride on the inside of the upper).

Install the carrier in the upper and you are ready to go to the range.

Before you load up to fire the first time, put 2 drops of clp in each exhaust hole in the side of the carrier, then lock the bolt back, insert a mag and blast away.

Enjoy.

 

[m1gunner]

Also, get some USGI or better quality mags. New aluminum mags need to be checked for rough feedlips.

If your brass has strong longitudinal scratch marks after chambering from the mag, lightly relieve (one or two light strokes with some 320 wet or dry paper) the rough edge under the feedlips, or just fire 100 rounds through the mag to polish the roughness out.