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Posted: 12/26/2012 10:00:44 PM EDT
I'm about to buy a buffer tube but I don't know if it should be Mil Spec or Commerical.

I just need it to match my code red firearms stripped lower.

The lower is marked as "mil spec" but the cheap-o buffer tube I found for 30$ is marked commercial.

Will they work together or whats the low down.

Thanks for help !
Link Posted: 12/26/2012 10:08:39 PM EDT
[Last Edit: 12/26/2012 10:12:45 PM EDT by RacerXXL]
The difference between the two is in the dimensions on the portion of the tube the stock slides over. A commercial tube only works with a commercial stock and a mil spec tube only works with a mil spec stock. Either tube will thread into your lower.

Link Posted: 12/26/2012 10:34:23 PM EDT
It wont strip out my lower will it?

I've read that if the threads are the wrong size. they won't properly fit into the low and you can end up damaging the lower by stripping the threads.

You got any info about this?
Link Posted: 12/26/2012 10:37:11 PM EDT
[Last Edit: 12/26/2012 10:37:26 PM EDT by RacerXXL]
Every AR I have owned started out with a commercial stock/tube and was later changed to a mil spec stock/tube. If there is a difference at the threaded end it's news to me.
Link Posted: 12/26/2012 10:41:10 PM EDT
Alright thanks buddy. I'll take your word as truth and order that buffer tube tonight.

The reason I'm ordering it without my lower in hand is because I've read the FFL might require me to turn it into a rifle so the 4473 can be filled out as a rifle.

Otherwise I have to go pull A pistol permit up at the local sheriff office.
Link Posted: 12/26/2012 10:42:08 PM EDT
There is no difference in the thread. The difference is with the stock body as mentioned above. Commercial w/commercial and Mil Spec w/Mil Spec.
Link Posted: 12/26/2012 10:45:59 PM EDT
IMHO there is no difference in the strength either, in this climate get what you can.
Link Posted: 12/26/2012 11:10:57 PM EDT

Originally Posted By AmericanGunLover:
Alright thanks buddy. I'll take your word as truth and order that buffer tube tonight.

The reason I'm ordering it without my lower in hand is because I've read the FFL might require me to turn it into a rifle so the 4473 can be filled out as a rifle.

Otherwise I have to go pull A pistol permit up at the local sheriff office.

A lower is processed as "other " on a 4473. Nothing else is required to build a rifle.
It's up to you to change it to a pistol or sbr. If you go that route.
Link Posted: 12/27/2012 12:10:30 AM EDT
you might want to read through this:

http://www.atf.gov/regulations-rulings/rulings/atf-rulings/atf-ruling-2011-4.pdf

If I understand that document correctly, and then personally speaking with an atf agent about this, you can build that lower into a pistol first, then to a rifle, then back to a pistol if you so choose, but at no time, do you want parts to be assembled that would be qualified as an sbr.

Link Posted: 12/27/2012 12:15:18 AM EDT
[Last Edit: 12/27/2012 12:16:17 AM EDT by AmericanGunLover]
Yeah I understand but in my state we have these old racist laws where the sheriff had the give you a "permit" to buy a pistol.
It was originally intended to keep blacks from owning a firearm.

We still have the permit system but they don't really check who's buying anymore. (white or black I mean)
so if the gun could be turned into a pistol, alot of FFL's will make sure you're not building one.

They won't mark it as "other" to cover their asses ( can't blame em...)

So if the FFL decides to play possum. I'll convert it right in front of him to a "rifle" configuration.

Edit: I'm in Charlotte, NC
Link Posted: 12/27/2012 3:27:44 PM EDT
As you can see in the posted diagram there is a difference in the threads. The commercial tube threads are smaller in diameter. There are folks who think that's a big deal for strength but a quick check in the Machinist's Handbook reveals that the slight difference in thread engagement makes almost no difference in strength. This is likely why the original producers of commercial tubes weren't worried.

There may be, however, a difference in the strength of the tubing. I think it is likely that the commercial tube is some sort of extrusion. The mil-spec tube is likely a forged piece.

I doubt the difference is important.
Link Posted: 12/27/2012 4:51:36 PM EDT
i am a complete newb.. in fact, first post, but the diagram above looks like there is 15/1000ths difference in the tube diameter at the threaded end... sorry for the newb question but is this just a mistake? Thanks!!
Link Posted: 12/28/2012 10:47:01 AM EDT
Originally Posted By Jkcoon:
i am a complete newb.. in fact, first post, but the diagram above looks like there is 15/1000ths difference in the tube diameter at the threaded end... sorry for the newb question but is this just a mistake? Thanks!!


Correct, the root of the thread is correct on a commercial tube but the threads are a bit truncated because they are cut into a tube which is a smaller diameter than nominal threads.
Link Posted: 12/28/2012 7:52:05 PM EDT
What I bought:

7075 T7 ALUMINUM - Milspec
Link Posted: 12/28/2012 10:28:31 PM EDT
Thanks, I just pulled mine out of the safe. I don't have calipers handy right now, but I checked to see if my buffer tube ended at a right 90 degree angle. I have milspec.
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