MilSpec or Comm Tube on my AR?


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HMMurdock
March 24, 2009, 07:48 AM
I am looking at getting a Magpul CTR stock (or the MOE, when I figure out what the difference is) and it says it is for MilSpec tubes, not Commerical. I have a Bushmaster AR I recently bought at a shop, new, with nothing changed on it. How do I know if I have a commerical or MilSpec tube?

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Gary G23
March 24, 2009, 01:23 PM
You can measure the diameter.
1.14" is milspec
1.17" is commercial

Every Bushy I have seen has been commercial.

tunnug
March 24, 2009, 01:49 PM
Easiest way to tell without measurement, take a look at the threads, if they stick out past the tube it's milspec, if they're even with the tube it's commercial.

bushmasterar15
March 24, 2009, 02:07 PM
Every bushy that I've had had a commercial tube on it.

SimpleIsGood229
March 24, 2009, 09:21 PM
Mil-spec tubes are generally 4- or 5-position, while commercial-spec are generally 6-position, if I'm not mistaken.

The CTR has a friction lock which removes any play between the stock and buffer tube, while the MOE does not. I highly recommend the CTR. I love mine.

1858
March 24, 2009, 09:46 PM
Yep ... Bushmaster has the commercial tube.

Here's a link to Bushmaster's FAQ section and their answer to the question of which size tube they use.

http://www.bushmaster.com/faqs/afmmain.aspx?faqid=1317

:)

Zach S
March 24, 2009, 09:49 PM
BM uses commercial stocks. You can either find a commercial CTR, or swap the buffertube out for a mil-spec (I used a stag).

As stated above, the CTR has a friction lock that locks up solid, the MOE lacks that friction lock, it just looks like the CTR, and rattles like an M4.

For future reference:

Mil-spec:
Threads larger than the buffertube. If you have calipers, the tube is 1.140 diameter, the threads are 1.188, +/- about .010" maybe .015"
4 or 5 position, although I think stags are 6. (edit: just checked mine, its 6)
The back is straight, doesn't sit flush with the stock when it collapsed.


Commercial:
Threads and tube are the same size, 1.170 (+/- .010)
The back is normally angled to match the stock, and is almost flush when collapsed.
6 position

CMMG used to use a cross breed between the two. The diameter and threads were mil-spec, but it was 6 position and has the slanted back to match the stock, like the commercial buffer tube. I believe they use mil-spec 5 pos tubes now.

1858
March 24, 2009, 10:05 PM
I stopped by my local gun shop this morning to buy a Troy front sight (HK folding battle sight) and ending up buying a bunch of other stuff too including a Vltor Emod buttstock (commercial) for my Bushmaster lower/POF upper along with 5 MagLevel™ PMAG™ magazines and a MagPul MOE grip. :D I wanted/needed the other items anyway so I figured I might as well get them while I was there.

:)

Pickles
April 15, 2009, 12:06 AM
Are Rock River Arms LAR-15's usually commercial, specifically the Entry Tactical?

<sorry in advance for dumb question, my Entry Tactical is currently in the mail on it's way to a local FFL>

Zach S
April 15, 2009, 11:41 AM
Are Rock River Arms LAR-15's usually commercial, specifically the Entry Tactical?
Commercial.

Commerical:

RRA
Bushmaster
DPMS
Double Star
Sabre Defense(?)

Mil-Spec:
CMMG
Stag
Noveske
CD
S&W
LMT
Colt
Spike's Tactical (I think)

I dont know about Armalite (mil-spec, I think), and I dont feel like searching for the much hated chart.

On a side note, it would appear that Mil Spec buffer tubes are becoming the standard, with only a few companies not using them.

If you by a no name collapsible stock, assume its a commercial. Most aftermarket mil spec stocks are advertised as such.

yehork
April 17, 2009, 05:29 PM
As a side note, DPMS offers both Commercial and Mil-Spec tubes, so you could have either if you have a DPMS.

Our base model rifles come with the commercial tube, except the Mark 12 which has a Mil-Spec and the Mil-Spec tube is an upgrade for others.

The easiest way to tell the difference on a DPMS is the commercial tube we sell is a 6 position and the Mil-Spec is a 5 position (including fully open and fully closed).

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