[thermal_scorpion]

I'm looking at picking up a new stock for my XCR and I have the Folding/Collapsing M4 Hinge w/ Button piece already. My question is do I need to get an extension tube that is milspec or commercial to fit it?

Thanks for any help.

 

[aziator]

I believe that they are Milspec but I am sure others will chime in for a 100% answer.

 

[ny32182]

I don't think the difference between buffer tubes is in the threading. i.e. any in spec AR receiver (and by inference, the XCR adapter) should be able to accept either a milspec or commercial tube. The difference is in the diameter of the rear portion of the tube, I believe. I think the milspec tube is slightly smaller. So, you want to match a milspec stock to a milspec tube/commerical stock w/ commercial tube, if possible. I think worst case scenario, you can put a commercial stock on a milspec tube (with some additional rattle), but I don't think you want to try to squeze a milspec stock onto a commercial tube.

So like I said, my understanding is that the RA adapter should be able to be used with either setup. Maybe Terra can come along and confirm.

 

[Sean K.]

I don't think the difference between buffer tubes is in the threading. i.e. any in spec AR receiver (and by inference, the XCR adapter) should be able to accept either a milspec or commercial tube. The difference is in the diameter of the rear portion of the tube, I believe. I think the milspec tube is slightly smaller. So, you want to match a milspec stock to a milspec tube/commerical stock w/ commercial tube, if possible. I think worst case scenario, you can put a commercial stock on a milspec tube (with some additional rattle), but I don't think you want to try to squeze a milspec stock onto a commercial tube.

So like I said, my understanding is that the RA adapter should be able to be used with either setup. Maybe Terra can come along and confirm.

You are correct. The threading is the same. Commercial AR tubes do not "step down" ever so slightly before the threading starts on the tube. Mil-spec tubes do. A mil spec stock will not fit on a commercial tube, but a commercial stock will fit (loosely) on a mil-spec tube.

 

[thermal_scorpion]

Thanks for the info. So it sounds like I just need to make sure to get all one type or the other but the threading should work fine on the adaptor either way.

Thanks!
Garth

 

[aziator]

Yeah, not sure what I was thinking when I answered, I knew that the threading was the same. Glad they go you taken care of.

 

[thermal_scorpion]

Now I just have to find a stock I like.

 

[Candidus]

This diagram illustrates the difference between mil-spec and commercial buffer tubes.

 

[SemiCircle]

Great diagram, thanks man!