Houdini buffer retainer on my AR-15

[hadmanysons]

I was at the range today and after three rounds my ar failed to fire. That of course annoyed me but I attributed it to a stiff primer and took another shot. Click.

I proceeded with the take-down and my buffer and spring go flying out like a rocket. Who knows where my retaining pin was or went and i found the retaining pin spring lodged in the BCG.

I took it back to where I bought and they're sending back to the manufacturer. Has this happened to anyone else or know of a persistent issue with things like this. It's a Smith and Wesson M&P15A.

 

[taliv]

dang, haven't heard of that one before

how many rounds had you put through it previously?

it's not clear why it failed to fire the first and second times though.

 

[Dr. Tad Hussein Winslow]

Dang that stinks...keep us updated. I offer no help unfortunately.

 

[dispatch55126]

Is the buffer tube chipped where the retainer pin use to be? I've seen photos in the past where the tube chipped causing the retainer pin to come out.

 

[Loomis]

I'd say your buffer tube retaining ring loosened up. Did you notice the buttstock turning sideways?

 

[hadmanysons]

It's only got about 500 rounds through. I didn't notice any canting of the stock but I did see the threads on the lower receiver a little scraped by something passing over it, probably the buffer. It's on its way back to Smith and Wesson right now in case it's a material/workmanship defect. At least if I have to many more problems with it I can drop the lemon bomb and get a new lower receiver.

 

[Loomis]

Well, the only other thing I can think of is that the clearance between the bolt and the buffer retaining pin was too close. The bolt struck the retaining pin and ripped out a chunk of your buffer tube on it's return to the upper receiver. Also, releasing an open bolt when there's no round to chamber puts a slightly greater stress on the buffer retaining pin. If your buffer retaining pin slot is slightly oversized and your buffer tube isn't quite up to snuff, slamming the bolt home on an empty chamber could conceivably cause a chunk of buffer tube to rip out when the buffer strikes the buffer retaining pin...and then knocks it out of it's slot.

 

[hadmanysons]

I just got it back from Smith and Wesson today. Holy crap! I guess they took the holidays off. I'm gonna shoot it Saturday. Wish me luck.

 

[Kind of Blued]

Did you/can you/will you run it through a basic function test before you take it out?

I'm guessing S&W didn't do any 'splainin'?

 

[hadmanysons]

I'm gonna clean it today and then do a function test. And no, they didn't explain a thing. Only thing I can think of is the buffer tube wasn't screwed in far enough.

 

[hadmanysons]

Works like a champ. Who knows what happened. As long as it doesn't happen again.

 

[45B@cav]

I've seen this a couple time in the Army. What happens if it's a carbine is the spanner nut was not tight and the reciever extension AKA buffer tube backed out just enough that the retainer got past it. If it has a A2 stock then the buttstock screw got loose and the retainer got past. Some manufacturers don't seem to think you have to stake the spanner nut or put thread lock on the buttstock screw.