10/15 upper won't lock

[wastedimage]

I just got my 10/15 upper in the mail and it seems to fit well but I can't get the damn thing to lock back. It's like the bolt isn't engaging with the internals at all. Just slides freely. My 10/45 and 10/31 uppers both work fine. Anyone have ideas?

 

[m11stuff@hotmail.com]

Are you saying that after installing the upper and releasing the IRM latch, that it will not cock back and catch the bolt?

Who is the manufacturer of the lower receiver?

 

[m11stuff@hotmail.com]

Also, how far back can you pull the charging handle? It should stop about .200” before bottoming out on the side of the lower receiver.

 

[rparsons3]

I had same problem, had to sand off a tiny bit off the sear engagement surface, cocks and runs fine now. I hesitated before I took off the sear material, even a little bit but so far so good. My gun was made by Sam from a registered flat. I even compared the length of several sears I have put up, none of them were exactly the same. (I have 3 mac 10s so I had spares put up).

 

[wastedimage]

Are you saying that after installing the upper and releasing the IRM latch, that it will not cock back and catch the bolt?

Who is the manufacturer of the lower receiver?

Yes. It’s a powder springs mac.

 

[wastedimage]

Seems like it’s going back all the way? What’s the best way to measure this, .2 seems pretty small.

 

[m11stuff@hotmail.com]

With the IRM assembly installed in the upper and the upper installed on the lower, cock and release the IRM latch allowing the bolt to go forward. Cock the bolt back as far as it will go and measure the horizontal distance from the back of the charging bar to the edge of the right side of the upper receiver. This distance should be about .200”.

 

[wastedimage]

With the IRM assembly installed in the upper and the upper installed on the lower, cock and release the IRM latch allowing the bolt to go forward. Cock the bolt back as far as it will go and measure the horizontal distance from the back of the charging bar to the edge of the right side of the upper receiver. This distance should be about .200”.

I must be thinking about this wrong, this seems like the left side but I'm not sure what else there is to measure? I measured this https://imgur.com/t1bqkSA looks like it's about .200. I put some calipers in there and it said .199 once I pressed them together from pulling back the handle. This is pushed back all the way. Does it seem right? The IRM latch releases fine but pushing past that moves almost no further back. I did notice some marks on the sear that I think are new.

 

[m11stuff@hotmail.com]

Yes, that is the correct place to measure and your measurement is good. Please e-mail me and I will let you know what else to measure and provide more troubleshooting.

M11stuff@hotmail.com

 

[wastedimage]

m11stuff had me squared away inside 15 mins after I got his email. I had to answer one entire additional question lol. The rubber buffer was the culprit.

 

[beltfed]

Sounds like they way mine operates. Pull charging handle back will not lock back on sear. I need to pull back with more force to get sear
to catch. It has run perfect in semi or full for over 100 rounds.
Last time at the range I put a 308 suppressor on and it started to do a 2 or 3 round burst in semi.
Almost like I needed to turn the gas up, I would think the suppressor would add pressure.
Next time I'll have tools to adjust.

 

[rparsons3]

m11stuff had me squared away inside 15 mins after I got his email. I had to answer one entire additional question lol. The rubber buffer was the culprit.

What did you have to do to it, put in a thinner buffer, be nice to know.

 

[m11stuff@hotmail.com]

1/4” buffer instead of standard 3/8” buffer.

Same buffer we use in the MAX-11A1/15.

 

[wastedimage]

Took it to the range today. Functioned perfectly with all the mag variations I had. No problem doing short bursts or long runs.

 

[wastedimage]

What did you have to do to it, put in a thinner buffer, be nice to know.

I sliced off the difference with a Dremel to make sure it was just the 3/8->1/4 quarter thing. It worked right way. Lage sent me a proper 1/4 spacer too so now I have a pretty one to destroy