View Full Version : Buffer tube - full length - ? thread size ?

January 19, 2013, 02:03 AM
I'm trying to put together and buy parts for an AR 15. I'm having a hard time comprehending this buffer tube situation. I have a MP 15 lower receiver. I'm looking to buy a full length buffer tube, and put an A2 stock on. Now, so I believe, the major diameter of the male threads on milspec tube is 1.185, and commercial tubes threads are 1.170, difference of .015
This seems like alot. I want a good fit where it threads together. Now, someone just broke news to me full length buffer tubes arent milspec or commercial. If this is true, what thread size is it? What do i need to thread into my S&W mp 15 please??

January 19, 2013, 07:27 AM
Thread diameters are all the same. Tube diameter is different and threads can be rolled or cut.


January 19, 2013, 08:34 AM
Just buy the A2 stock kit with buffer, tube and spring and it will be fine. The threads in the receivers are all the same and the only thing that matters on M4 style collapsible stocks is the diameter of the outside of the tube. Mil Spec stocks wont fit commercial tubes and commercial stocks will be very loose on a Mil spec tube. Fixed stocks no worries.

January 19, 2013, 10:45 AM
The guys above are right, the threads are the same. A complete A2 kit will fit your lower. Also, there are stocks similar to the A2 (or the slightly shorter A1) that fit your existing S&W milspec tube, assuming you have a complete S&W lower. Magpul just introduced one at the Shot Show that may fit but I'm not 100% which tube it uses.

January 19, 2013, 12:09 PM
ok, what do you guys think of this kit. I know it doesnt come w/ a stock, but I wasn't able to find one that did that was new. http://www.ebay.com/itm/321057009774?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
this is where I got the notion that threads were of diff dia. http://www.google.com/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=1&cad=rja&ved=0CEEQFjAA&url=http%3A%2F%2Fwww.m4carbine.net%2Fshowthread.php%3Ft%3D109917&ei=a9L6UOOqCeyr2AXRjoHoAw&usg=AFQjCNE1xY0U3BOjt9_q4yAYTMS8gmlRPg&sig2=lZ9W_NbMDsdfry_7dviwng&bvm=bv.41248874,d.b2I

January 19, 2013, 01:46 PM
That should work but seems a little steep to me. I actually paid less than that for the complete kit that included the A2 stock. I replaced mine with an Ace skeleton stock so if you want the A2 drop me a PM and I'll tell you about it. that is minus the the buffer, tube and spring.

January 20, 2013, 01:14 AM
Thanks Slappy, I thank you for helping me out on my threads. I will be PMing you. Yes its steep. Funny thing is, it was nine dollars less when I pasted it on there.

January 20, 2013, 08:48 AM
ok, what do you guys think of this kit. I know it doesnt come w/ a stock

At that price you should get the butt stock. Shop around, I know Midway has them in stock, check Rainier Arms and others. $70+/- should buy a complete A2 type RE/butt/buffer.

January 20, 2013, 09:00 AM
$89 is ridiculous.
Here is what you need"
That's $38 plus shipping. They are all "in stock" as of 10am but don't know how long they will last. It's a shame that no one seems to have it all in one place so you don't have to pay separate shipping on each but that is the nature of things right now I suppose.

January 20, 2013, 10:11 AM
Model 1 sales has complete A2's for $55


January 20, 2013, 10:44 AM
There you go. Now that I see it, that is the same one I bought for mine. I think it came from midway or somewhere though. One thing about them, even though they say they are black, they actually are an odd gray/green color so I painted mine with semi-flat black spray paint.