Bolt not locking back after last round fired

[Sig226GuyNJ 128]

What stock is it?

Just a standard 6 position collapsible stock.

http://en.wikipedia.org/wiki/File:MP15.jpg

It's the same stock that came with the M&P15, but not the exact same one as there was no way to collapse the original one all the way.

[Displaced Texan 11,777]

Jim,

 

Let me get this straight. You changed the old stock out, and now the buffer/ spring has play inside the receiver extension?

 

What exactly did you change? Stock only?? Knowing what I know about the 'compliant models, I doubt you changed just the stockS Did you replace the receiver extension?

I guess it's hard for me to understand what the issue is without seeing it.

 

I'll be at the Knoxville airport in about an hour, I'll have a couple of hours to kill if you want to call me and discuss it.

 

Jeff

[checko 180]

 

Is it this? If you didn't have hat pin you probably couldn't separate the receivers I'm not sure what you mean by sliding back and forth. Is it possible you had one of those compliant stocks meant to use a rifle buffer bit made to look like an m4 stock? I would think this would cause cycling trouble though.

[Displaced Texan 11,777]

The buffer retention pin was my exact thought.

Thanks for posting that, Checko

[Sig226GuyNJ 128]

Jim,

 

Let me get this straight. You changed the old stock out, and now the buffer/ spring has play inside the receiver extension?

 

What exactly did you change? Stock only?? Knowing what I know about the 'compliant models, I doubt you changed just the stockS Did you replace the receiver extension?

I guess it's hard for me to understand what the issue is without seeing it.

 

I'll be at the Knoxville airport in about an hour, I'll have a couple of hours to kill if you want to call me and discuss it.

 

Jeff

Thanks Jeff. Yes. The receiver extension was still in the "new" stock that I put on. The original stock and receiver extension were both taken off.

[Sig226GuyNJ 128]

 

Is it this? If you didn't have hat pin you probably couldn't separate the receivers I'm not sure what you mean by sliding back and forth. Is it possible you had one of those compliant stocks meant to use a rifle buffer bit made to look like an m4 stock? I would think this would cause cycling trouble though.

It seems as thought the buffer is moving around inside the receiver extension, if that makes any sense.

[Sig226GuyNJ 128]

The buffer retention pin was my exact thought.

Thanks for posting that, Checko

The retention pin is on just fine. I'll take a video of it tonight and post it. Hopefully you gents can hear what I'm talking about. It could very well be that since the stock is so old, it just rattles a bit.

[High Exposure 5,674]

One more question for the experts. While troubleshooting my AR, I put in a different stock on. Still using the same buffer and spring. However, the buffer now slides a bit up and down inside the tube. My old stock had something in it to prevent this from happening. What is it? And where can I buy one?

I am not tracking and I suspect that there are some nomenclature issues at play.

 

The buffer is the weighted clipped-cigar shaped peice with the nylon end.

 

The buffer rides the action spring (sometimes incorrectly referred to as the "buffer spring").

 

The buffer and action spring reside inside of the receiver extension (sometimes incorrectly referred to as the "buffer tube").

 

Finay the stock is the external plastic piece that slides over the receiver extension and actually comes in contact with your shoulder.

 

If your stock is what is loose on the receiver extension I suspect there is a discrepancy with a commercial-spec stock over a mil-spec receiver extension.

 

If the actual buffer is "loose" or rattling in the receiver extension that's no big deal at all. It should move freely with plenty of clearance. It also may be a result of a commercial-spec tube larger inside diameter.

[checko 180]

Tube shouldn't move. Retainer and castle nut should keep it it place tightly. If its just hitting the walls I don't see an issue, that's normal. I don't know what you mean by the old one had something that prevented it.

 

HE is probably right. Edited to clarify.

 

[Sig226GuyNJ 128]

I am not tracking and I suspect that there are some nomenclature issues at play.

 

The buffer is the weighted clipped-cigar shaped peice with the nylon end.

 

The buffer rides the action spring (sometimes incorrectly referred to as the "buffer spring").

 

The buffer and action spring reside inside of the receiver extension (sometimes incorrectly referred to as the "buffer tube").

 

Finay the stock is the external plastic piece that slides over the receiver extension and actually comes in contact with your shoulder.

 

If your stock is what is loose on the receiver extension I suspect there is a discrepancy with a commercial-spec stock over a mil-spec receiver extension.

 

If the actual buffer is "loose" or rattling in the receiver extension that's no big deal at all. It should move freely with plenty of clearance. It also may be a result of a commercial-spec tube larger inside diameter.

 

Ok. So I just got off the phone with my buddy who helped me change out my stock and receiver extension. I got more clarification now. The original stock and receiver extension that Smith and Wesson used was a rifle length extension receiver. Therefore, they put a spacer in there to prevent the carbine buffer from moving around if I'm understanding correctly. I had assumed the new receiver extension and stock was also rifle length, but got clarification that it's a carbine length. So I guess what I hear is not the buffer moving around, and will just chalk it up to it being an old stock that has a little bit of play in it.

[checko 180]

Called it.

[Sig226GuyNJ 128]

Called it.

Thanks for your help everyone!

[Displaced Texan 11,777]

Glad you're sorted out.

[PK90 3,573]

I am still confused.

 

First, you have the stock in a fixed position, right?

 

Secondly, what little piece are you talking about? The A2 spacer?

 

Sent from an undisclosed location.

 

 

[checko 180]

I am still confused.

 

First, you have the stock in a fixed position, right?

 

Secondly, what little piece are you talking about? The A2 spacer?

 

Sent from an undisclosed location.

Sounds like a spacer that goes inside a rifle length tube to make it fit a carbine buffer and spring.

[PK90 3,573]

I've never seen one become displaced. I always thought it was part of the extension and not a separate part.

 

Sent from an undisclosed location.

 

 

[Sig226GuyNJ 128]

Sounds like a spacer that goes inside a rifle length tube to make it fit a carbine buffer and spring.

 

This is correct. I felt and heard some movement, and automatically assumed I needed a spacer in the receiver extension, since I had/have one on the original one that came with the rifle. But after speaking with my friend, he informed me the new one I have is carbine length, therefore no spacer needed.