AR-15 Problem

[ldlfh7]

Yesterday i was shooting my AR15 and after a bit click. Tried a couple more and click again. Tool the upper off and noticed the buffer retainer spring was in the action and mangled. Looked like the hammer may have smashed it or something. Also, the buffer retainer had a small indention on the bottom of it, and was not it the hole it is suppose to live in.

Any ideas what may have caused this failure?
I have bought new lower hardware parts, but somewhat concerned why it happened in the 1st place?

Its an A2 fixed stock if that matters on a delton lower and psa carbine length upper. This has been solid for several thousand of rounds. Did a pin just wear out or something or is there a more serious problem going on?

 

[ClickClickD'oh]

If the buffer retainer spring got into the action, I'm sure that the buffer retainer has also gone on walk about. This generally mean that your buffer tube isn't screwed in far enough. The buffer tube should be screwed in far enough that it's lip is over the edge of the buffer retainer, preventing it from coming out.

 

[ldlfh7]

Yes, the retained took a walk as well. Is it normal for the buffer tube to work its way out gradually over time?

 

[hdwhit]

ldlfh7 wrote:
Is it normal for the buffer tube to work its way out gradually over time?

Yes, unless the castle nut is properly staked to the receiver.

 

[bfoosh006]

"Yes, unless the castle nut is properly staked to the receiver."

Correct answer... but just to clarify and no offense, stake the Rifle length buffer tube as well. ( No Castle nut for a rifle length tube )

 

[ClickClickD'oh]

Yes, unless the castle nut is properly staked to the receiver.

Never seen a castle nut on an A2 stock.

 

[ants]

Never seen a castle nut on an A2 stock.

ClickClick is correct, I think the others just didn't catch the A2 reference. They saw PSA carbine upper and just assumed.

I'm sure Idglf can get a good experienced person to help him repair and reassemble his rifle.

 

[FL-NC]

Yep. Loose receiver extension/buffer tube.

 

[ldlfh7]

Problem resolved. Buffer tube was loose. Replaced the damaged parts and back in action. Thanks.

 

[wally]

Replaced the damaged parts and back in action.

One of the best features of the AR platform. Parts are cheap and plentiful and easy to replace.

 

[Tirod]

Au contraire, best feature of the AR is that the owner can fix it himself, no gunsmith needed. The most difficult job on the AR is attaching a barrel extension to a barrel - that takes headspacing, drilling the gas port, etc. Complete barrel assemblies make it a non problem for the builder or owner.

It was definitely part of the engineering solution Stoner incorporated - to make assembly as problem free as possible. Expensive labor and highly trained technicians aren't required, nor is a gun shop full of presses to fit barrels into receivers while simulataneously setting headspace.

On the other hand it's not actually Legos, little things like screwing the buffer tube down far enough to catch the buffer retainer to keep it in it's hole are part of the tips and tricks. A2 or not it's required. How you keep it there is something the aftermarket has also solved, there's now a "castle nut" which has a shaped spring tooth which eliminates staking. That allows for easier disassembly when needed down the road.

Military grade M16/M4's get staking, rivets, peened pins, etc to remain together in harsh service, civilian grade AR's can benefit from a host of aftermarket parts like above, including tapped and set screwed safety detents, etc., so that little jewel doesn't make like a 1911 plunger on disassembly, either.

It's all about the engineering, there is far more than the usual interwebs discussion of DI. Stoner and crew thought about every detail and how it would affect things.