Warning

 

Close
Confirm Action

Are you sure you wish to do this?

Cancel Confirm
AR15.COM
7/4/2017 2:11:38 AM EDT
I'm considering doing a build, and have been window shopping lower build kits.  It seems some of the PSA kits include "Mil-Spec diameter" receiver extensions, which I assume means 6061 aluminum rather than 7075 that would be actual Mil-Spec...not just in diameter.

If the description for the kit just says "Mil-Spec buffer tube assembly" but doesn't actually say 7075 or 6061, is it safe to assume one or the other?  i.e.

http://palmettostatearmory.com/psa-freedom-moe-lower-build-kit-black.html "Mil-Spec"
http://palmettostatearmory.com/psa-defender-moe-lower-build-kit-no-ambi-safety.html "Mil-Spec diameter"
http://palmettostatearmory.com/palmetto-state-armory-moe-lower-build-kit-black-with-qms-trigger.html "Mil-Spec diameter"

I'm assuming the latter two are 6061 extensions, and the first one might be 7075?
7/4/2017 8:12:07 PM EDT
[#1]
AFAIK, unless they state, specifically, that's it's 7075.... it's NOT.
7/6/2017 3:56:23 AM EDT
[#2]
Quote History
Quoted:
AFAIK, unless they state, specifically, that's it's 7075.... it's NOT.
View Quote
That is not what PSA told me. Perhaps they led me astray. I was informed that this product comes with a 7075 receiver extension: Defender Lower
7/6/2017 11:31:39 PM EDT
[#3]
Quote History
Quoted:


That is not what PSA told me. Perhaps they led me astray. I was informed that this product comes with a 7075 receiver extension: Defender Lower
View Quote
Sorry, but that's a 6061 "mil spec DIAMETER" tube (as described in the ad), not a "mil spec 7075" tube.
Mil spec is mil spec (size/material/manufacturing type). Mil spec "DIAMETER" denotes that it's mil spec in diameter ONLY (not construction).
7/7/2017 12:24:40 AM EDT
[#4]
Hopefully this thread helps answer your questions

buffer tube woes
7/10/2017 4:06:31 AM EDT
[#5]
Quote History
Quoted:

Sorry, but that's a 6061 "mil spec DIAMETER" tube (as described in the ad), not a "mil spec 7075" tube.
Mil spec is mil spec (size/material/manufacturing type). Mil spec "DIAMETER" denotes that it's mil spec in diameter ONLY (not construction).
View Quote
I am aware of the differences. PSA was certain that this was 7075. In fact, I had the receiver extension exchanged for a 7075 for piece of mind. The two looked identical. There was no visible difference inside or out.
7/10/2017 8:02:44 PM EDT
[#6]
I ended up going with this kit:
http://palmettostatearmory.com/moe-lower-build-kit-black.html
which says only "Mil-Spec buffer tube", twice.  Nothing about diameter.  Also nothing about the actual type of aluminum.  From what I've read, there's no way to tell the difference between 7075 and 6061 "mil-spec diameter" tubes, so you have to just trust the seller (or not).