HELP: Receiver Extension (Buffer Tube) Threads

[fenceline]

I'm currently working on assembling a Nodak Spud NDS18 lower. For a stock I decided to go with an A2 fixed stock combined with a Stormwerkz "AR-180B Stock Adapter Type 4".

I picked up a Cadex "DPMS Extension Tube P/N 175-00012" in the hopes it would all work. The problem I have now is that the extension tube will begin to thread into the Stormwerks mount and then seize half way on. It appears the threads are not the same. I had hoped that the DPMS threads would be the same.

Are the DPMS AR10 extension threads different than an AR15 extension's threads? Anyone have problems with the Stormwerkz adapter before?

 

[G37]

It gets halfway on? Maybe it's tight tolerances (i.e. the anodizing of both parts is causing the friction.)

You could isolate the problem quick with another ar15 tube if you have access to one.

Otherwise, try working your current tube in, twisting back and forth repeatedly to see if you can work it in (but double check the threads to make sure they're not getting galled.)

 

[fenceline]

It gets halfway on? Maybe it's tight tolerances (i.e. the anodizing of both parts is causing the friction.)

You could isolate the problem quick with another ar15 tube if you have access to one.

Otherwise, try working your current tube in, twisting back and forth repeatedly to see if you can work it in (but double check the threads to make sure they're not getting galled.)

I was thinking that might be a possibility. The DMPS tube finish is quite thin, almost like blueing or paint. The Stormwekz part is a thick finish, like parkerized.

 

[L42A1]

Try lubricating it as well

 

[fenceline]

Funny it was mentioned I should try another extension tube. I was so into making these two pieces work together I forgot I had another rifle sitting beside me with the same type of buffer extension.

Swapped them and got the dpms that wouldn't fit in the stormwerkz mount to fit into the milspec lower and took that buffer tube and it fit perfectly into the Stormwerkz mount. Tolerances are good to go on both. Just enough difference not to work the other way around though.

Thanks for helping me walk through it.