AR 15 action jam

[Crowman]

First time at range with new rifle, first time firing. After 25 rounds of PMC 55 grain FMJ ammo, the bolt jammed part way open and was stuck hard. Removed magazine and knocked out both take down pins. Removed upper and the recoil buffer retaining pin was down in the action and the retaking pin spring had been cut in two. Very puzzling. Fortunately I had a spare spring. Got the parts out of the action, reinserted the spring and retaining pin. Not sure how the pin is retained...looked like a flat on the buffer is all that holds it, and a slot in the bottom of the bolt appears to ride over it. No staking, no retainer. Reassembled rifle, test fired and had same failure after third round. Why is this happening?

 

[119er]

Assuming that it is an AR-15 with a telescopic stock, the receiver extension is not screwed in far enough or one of the parts is out of spec. This is probably also possible if it is the Fixed stock too.

Curious, how did you happen to have a spare spring with you?

 

[M-Cameron]

the retaining pin is held in place by the buffer tube, not the buffer its self.....the buffer tube should ride over the retaining pin like this:




if you can remove the retaining pin without taking off the butstock....chances are the pin spring is being chopped by the bolt or the buffer

 

[Crowman]

I ordered several spare parts kits off Amazon just after buying the AR556. Looked like a whole lot of small stuff that could go airborn at a moments notice. I normally keep spare parts around for "just in case".

 

[Crowman]

Thanks for the photo, I will check and see if the tube has the recess. Apparently, not screwed in enough. I will investigate.

 

[119er]

Man, you're prepared! Be aware that not all tubes have that notch for the pin as in the above photo. Some are just a small lip or protrusion that simply catches the large diameter of the retaining pin. If it is indeed loose, the wrench to tighten the castle nut is pretty inexpensive.

 

[M-Cameron]

just an FYI, the half-moon recess is not necessary......it may also look like this as well



just so long as the tube holds the pin in place, and the pin is able to move freely.

Man, you're prepared! Be aware that not all tubes have that notch for the pin as in the above photo. Some are just a small lip or protrusion that simply catches the large diameter of the retaining pin. If it is indeed loose, the wrench to tighten the castle nut is pretty inexpensive.

i didnt even bother with the wrench to tighten mine, just used a brass punch to spin the nut enough to tighten it up....then once you stake it, its not moving.

 

[Jackal]

Sounds like your buffer tube isnt screwed in far enough. This is why you dont buy "gunshow" or Facebook AR's, unless you know what to look for.

 

[rcmodel]

Looked like a whole lot of small stuff that could go airborn at a moments notice.

That just never happens if the gun is built right in the first place.

How do you think we have been fighting wars with them for over 50 years if the 'parts go airborn' all the time??

rc

 

[AJumbo]

I believe Crowman was referring to those parts that go flying away from the bench moreso than any that might separate during a fight.

 

[JO JO]

Did the OP say what rifle this is he said new rifle ?
Home buid or factory built ?

 

[rcmodel]

I ordered several spare parts kits off Amazon

I believe Crowman was referring to those parts that go flying away from the bench moreso than any that might separate during a fight.

Still, I've been running AR's since about 1971.

And I haven't needed a spare parts kit yet.

I keep a couple extra ejector springs & buffers, a cam pin, a firing pin, and an extra cotter key on hand.

But so far I've never needed them in all those years.

rc

 

[Crowman]

AR15 action jam

Yup, I mean all those little do-dads that go flying off the bench at the most awkward moments. Once had the recoil spring plunger from my 1911 shoot out the shed door and into the poison-ivy filled woods. Never found that sucker. Luckily I had a spare.

Just after I bought my AR 556, I got an armourer's tool kit with all the goodies plus several parts kits with all the little stuff that can get lost during disassembly, " just in case". Got fumble fingers in my old age...not as nimble as they once were. Also got smarter.


Guys, thanks for the help. The buffer tube was not in quite far enough to retain the plunger. Mine is one of the rifles that has a lip that protrudes about 1/32-1/16" along a 120 deg arc at the bottom of the tube. Once I saw your photos, I saw the problem and fixed it. Walked out in the woods to my rifle range and ran some Tula 55 grain FMG through ti with no problems.