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View Full Version : Mil-Spec Buffer Tube vs Commercial Buffer Tube


spdlinegsr28
02-12-2009, 5:24 PM
Hi Ya'll,

I'm having a brain fart here and needs someone wisdom on my issue...I seem to be confused, whats the difference between a Milspec buffer tube and a Commercial buffer tube?

How can you tell if you have them side by side?

Any input would be great!! Thanks a lot guys!!

hoffman259
02-12-2009, 5:37 PM
http://www.ar15.com/lite/topic.html?b=3&f=19&t=395320

bplvr
02-12-2009, 6:25 PM
I got 2 commercial Rock Rivers from Midway and the charging handle hit both of them . I used a file and black leather dye to fix them. Next time,Mil-Spec.

Casual Observer
02-12-2009, 6:28 PM
http://www.laruetactical.com/pics/BufferTube/CTR_Stock_Specs.jpg

rumble phish
02-12-2009, 6:31 PM
Mil-spec is better. Slightly smaller in diameter but it is forged aluminum, not extruded which makes it stronger even though it's slightly smaller.

freakshow10mm
02-12-2009, 6:33 PM
I've never heard of quality issues with the commercial type. Just because something is labled "mil spec" doesn't mean higher quality. For some reason ARFCOM loves that stuff. I've been building my own ARs for almost 10 years now and have built guns with both types of receiver extensions and never had an issue with the commercial type. The wobbles came from the "mil spec" tubes.

spdlinegsr28
02-12-2009, 7:28 PM
Wow thanks for the great inputs, but to your opinion which is better between the 2?

rumble phish
02-12-2009, 7:39 PM
a mil-spec tube is STRONGER. It's not because it's called mil-spec that makes it better, it's because of the type of aluminum used.

Forged = stronger

extruded = weaker

will it make a difference at the range or plinking? Probably not, but I like to know that it is stronger material.

nav195
02-12-2009, 9:20 PM
how can i tell if my magpul ctr is milspec or comm?

freakshow10mm
02-12-2009, 9:23 PM
Take the measurements and compare them to the above graphic which notes the differences.

philthy209
02-12-2009, 9:30 PM
Where can i get a milspec tube without being arse raped?

freakshow10mm
02-12-2009, 9:32 PM
www.army.mil

spdlinegsr28
02-12-2009, 10:06 PM
Well, I guess the CAA stocks works better with comm. stocks...I tried it on my other AR's and it wubbles...HHmmm..either I trade one of my Mils-spec tubes or buy a whole new butt stock...

spdlinegsr28
02-12-2009, 10:10 PM
Where can i get a milspec tube without being arse raped?

http://www.stagarms.com/product_info.php?cPath=19_28&products_id=275

Loner
02-13-2009, 6:38 PM
http://www.stagarms.com/product_info.php?cPath=19_28&products_id=275
Got mine today.

gn3hz3ku1*
02-14-2009, 11:27 AM
so why did they create 2 kinds of buffer tubes?

dieselpower
02-14-2009, 8:53 PM
so why did they create 2 kinds of buffer tubes?


From what I was told, when Colt started making the collapsing stock, they also started a lawsuit on any manufacture that tried to sell the same. That failed, but it lead to two types of tubes. I don't know if this is true, but with Colts past on lawsuits against other weapon manufacturers its a reasonable story.

FTR, just because its Mil-Spec doesn't mean anything. Mil-spec is being used as a measurement for the size of stock that will fit on it, and not how or what it was made with.

So saying a Mil-spec tube is: Stronger, better grade metal, or whatever is not quite right. You can buy a MIC (made in China), Mil-spec tube on e-bay for $10.00, or you can buy the exact same one for $45.00 thinking it was a true Mil-spec. the only way to protect yourself is to buy from a quality retailer. If you are doing that, then either size is good. A Bushmaster or Magpul Commercial Tube is just as strong, and of high grade as a Mil-spec...just not the same size diameter.

I have a CAA commercial which is lower grade metal, but is fine for what I do...I'm not going to use it as an anchor to repel down a cliff, and the stock has zero wobble, with a tight pull solid lock up.

Tony.
02-15-2009, 1:44 PM
how can i tell if my magpul ctr is milspec or comm?

Light some scented candles, get some bubbly, touch it gently behind the ears, whisper sweet nothings, then ask.....

-or-

You can look the the freaking chart on post 4

Cardinal Sin
02-15-2009, 2:12 PM
Light some scented candles, get some bubbly, touch it gently behind the ears, whisper sweet nothings, then ask.....

-or-

You can look the the freaking chart on post 4

Yeah but you know you like whispering sweet nothings to gun parts:p

lumpia
02-15-2009, 2:55 PM
The threads are the big issue between the 2. Commercial threads are not cut to full height and don't engage the receiver fully. More here:

http://m4carbine.net/showthread.php?t=101

dankelly
03-02-2009, 8:56 PM
It's been pointed out elsewhere that the mil-spec tube has higher threads that fit deeper into the receiver (see the above post and illustrations). I don't recall where I read it, but the post went on to say that some type of failures/breakage of the commercial tube occurred in the field, as a result of this inherent weakness of the threads.

Aside from this anecdotal information, seeing as how the RECEIVER THREADS ARE THE SAME (there is no mispec vs. commercial receivers - and if there is my skull is going to crack! the issue over the tubes is maddening enough), and the MIL-SPEC THREADS RUN DEEPER INTO THE RECEIVER THREADS, and maybe the mil-spec even uses stronger aluminum (so they say), it would seem one might as well select the mil-spec tube if given the choice. The VLTOR EMOD stock, to take just one example, is offered in both types, noting that 'The standard is Mil-Spec.'

RangemasterP226
01-13-2010, 10:14 AM
http://www.laruetactical.com/pics/BufferTube/CTR_Stock_Specs.jpg

Thanks for the graphic!

Mitch
01-13-2010, 11:42 AM
so why did they create 2 kinds of buffer tubes?

Very simple. Nothing to do with licensing.

The milspec tube requires rolled threads, which are challenging to machine on such a thin tube and also require an expensive mandrel as tooling. So a cheaper way to make a workable tube is to increase the outside diameter of the tube and cut the threads. That's your commercial tube.

Be careful going by the graphic above. Plenty of commercial tubes do not have the slant at the back.

slik556
01-13-2010, 3:26 PM
how can i tell if my magpul ctr is milspec or comm?

Light some scented candles, get some bubbly, touch it gently behind the ears, whisper sweet nothings, then ask.....

-or-

You can look the the freaking chart on post 4

:rofl: I'm glad someone said it, I was about to but I let it slide....

RichMac
10-22-2010, 6:16 AM
There is a $1 little gage for sale on Amazon that lets you tell which kind of tube you have. The gage is made by Tactical Intent, a company that is making buttstocks and rail covers. The gage is dirt easy, cheap and eliminates any question.

You can find it at:
http://www.amazon.com/gp/browse.html?ie=UTF8&marketplaceID=ATVPDKIKX0DER&me=A36ZAOEPX7I0P8

dlouie87
10-22-2010, 11:01 AM
just go with mil-spec.... better in the long run or keep all the buffer tubes/stocks one way. (commercial or milspec)

stitchnicklas
10-23-2010, 12:27 PM
mil-spec is better imho because more modifications and parts seem to be available

3rd_gear
10-30-2010, 2:41 PM
I got 2 commercial Rock Rivers from Midway and the charging handle hit both of them . I used a file and black leather dye to fix them. Next time,Mil-Spec.

Please explain how this can happen, I don't understand how this is possible.

Noobert
10-30-2010, 2:45 PM
Necrothread!

Thecrazyone1
11-01-2010, 9:16 PM
Are castle nuts all made the same? What about the buffer inside of the tube? Are the inner diameters the same for commercial and mil spec. I ask because I ordered a complete stock assembly but the buffer tube was commercial and didn't retain the detent thing for the buffer while being able to connect the upper to the lower. So I ordered a mil spec buffer tube seperatly. Can I use all of the rest of the parts that came with the commercial tube in the milspec tube?

liquidmx
11-02-2010, 9:30 AM
Honest question... Since the milspec and commercial buffer tubes have different threaded diameters (based on the above graphic)...wouldn't that mean the mislpec should (ideally) fit into the lower tighter(better tolerance) than the commercial (assuming they are both going into a true "milspec lower"?

I know the whole "milspec" term gets thrown around REALLY loosely...just curious what others thoughts on this are? Maybe I am reading the dimensions incorrectly?

obpwankel
02-02-2011, 1:43 PM
Ah, man, riflegear gave me the wrong buffer tube! I told the guy specifically mil spec! no wonder this thing won't slide forward or locks. Man, such bad luck I have. Just "finished" buidling the ar today, and this happeneds...

tacticalcity
02-02-2011, 1:56 PM
Both commercial and milspec will work just fine on your lower. The graphic implies otherwise, but that is not correct. There will be no movement or play between the threaded end of the tube and threaded portion of your lower with either tube.

obpwankel
02-03-2011, 2:50 AM
Something is not right then. My stock would not slide forward or locks. From the pictures, looks like I got the mil spec threads, but the locking holes looks from the commercial tube. The hell?

What should I doo? I pay $150 for this kit.

SJgunguy24
02-03-2011, 3:02 AM
Something is not right then. My stock would not slide forward or locks. From the pictures, looks like I got the mil spec threas, but the locking holes looks from the commercial tube. The hell?

What should I doo? I pay $150 for this kit.

Mil spec stock on commercial tube, get a new tube.
For the record, all mil spec means is that part is made to a standard, a specification the US military has established in order for that part to be considered for purchase. Since everybody wants a cut of that market, you'll see an abundance of "mil spec" parts, the bonus, they should all work together,

Airrixd
02-03-2011, 7:35 AM
"Are castle nuts all made the same? What about the buffer inside of the tube? Are the inner diameters the same for commercial and mil spec. I ask because I ordered a complete stock assembly but the buffer tube was commercial and didn't retain the detent thing for the buffer while being able to connect the upper to the lower. So I ordered a mil spec buffer tube seperatly. Can I use all of the rest of the parts that came with the commercial tube in the milspec tube?"

I was wondering the same thing. Are the stock components (spring, castle nut, etc.) interchangeable between Mil and commercial tube?

obpwankel
02-03-2011, 8:12 AM
Ok, guys.

I've found the problem, and it's the stock. after a good observation, and messing with the lever adjustment, i see what looks like the pivot lock(dunno the right term word for this mechanism) would not go all the way down how it should. so before it reach there, obviously the buffer tube would stop before reaching the locking-holes. spring too short/long/strong? lever? I don't know.

I have a defect stock.

I have to manually push force using both my thumbs in order to make this thing work. you guys do comprehend what im saying/problem here? I don't know if i am making any sense

just to clarify, yes, i just find out i have the mil spec. from that pic diagram it shows that the buffer extension it has 4 and the commercial has 6. well, for some odd reason mil spec has/ or has always been 6 now?

thanks, for those who are helping me.

dieselpower
02-03-2011, 8:13 AM
"Are castle nuts all made the same? What about the buffer inside of the tube? Are the inner diameters the same for commercial and mil spec. I ask because I ordered a complete stock assembly but the buffer tube was commercial and didn't retain the detent thing for the buffer while being able to connect the upper to the lower. So I ordered a mil spec buffer tube separately. Can I use all of the rest of the parts that came with the commercial tube in the milspec tube?"

I was wondering the same thing. Are the stock components (spring, castle nut, etc.) interchangeable between Mil and commercial tube?

continuing this necro-bump

yes and no.
The castle nut in cheap commercial kits is of course cheap. The threads are once again cheaply made and are not the exact as a mil-spec tube will be. Yes it will fit.

The end plate. kinda hard to goof this up, but when they do...boy does it show.... yet again cheaply made, thin, sometimes the metal is so weak a good twist on the tube will snap off the indexing tab. That brings up a major flaw seen in many UTG commercial kits. The end plates indexing tab isnt straight up and down. So when the buffer tube is tightened down the stock is canted. You can see this by extending the stock all the way back and holding the AR15 like a pistol with your arm extended, look at the back of the stock..it will be leaning to the left or right.

The spring. Cheap metal, sometimes they use two springs together to provide the force needed of 1. Non-coated, rusting. some are only good for a limited amount of time, after a couple hundred uses it will be nearly dead.

The buffer. most are filled with BBs or pieces of metal, I have seen them filled with metric nuts. the bumper is made of a plastic that breaks apart, the weight is a total unknown. The higher end companies offering commercial buffers are well made...the UTG ones I don't trust. There is a lot of re-branding so if you are paying $22 for an entire Stock kit expect the buffer to be a joke.

The tube. see all the post above. The threads are the big problem. They are cut into the tube, weakening the tube itself. From cheap manufactures they wont even be the correct shape. From higher end companies they are good, just don't hang on the tube like an ape...LOL I've used Bushmaster, RRA and CAA tubes and they were ok. I have also seen a commercial tube broken.

The stock not much to go wrong, but once again on cheap ones they really cheap out.

and that ends this necrobump for me...lol search more on them I have also posted MS paint pics detailing the problems of commercial tubes.

dieselpower
02-03-2011, 8:20 AM
Ok, guys.

I've found the problem, and it's the stock. after a good observation, and messing with the lever adjustment, i see what looks like the pivot lock(dunno the right term word for this mechanism) would not go all the way down how it should. so before it reach there, obviously the buffer tube would stop before reaching the locking-holes. spring too short/long/strong? lever? I don't know.

I have a defect stock.

I have to manually push force using both my thumbs in order to make this thing work. you guys do comprehend what im saying/problem here? I don't know if i am making any sense

just to clarify, yes, i just find out i have the mil spec. from that pic diagram it shows that the buffer extension it has 4 and the commercial has 6. well, for some odd reason mil spec has/ or has always been 6 now?

thanks, for those who are helping me.

step 1.
Run your finger over the threads...are they RAISED or are they cut into tube? Look at them close. This is the difference that tells the story, not the number of holes or the angle the back is cut at.

Look at the screw in the pin, does it have a roll pin going through it? Who made this stock kit? It is sometime possible to adjust the throw of the lever. By adding a shim under the lever, you decrease the depth of the holding pin. Some can even be screwed in to decrease the lock up detent.

obpwankel
02-03-2011, 11:01 AM
step 1.
Run your finger over the threads...are they RAISED or are they cut into tube? Look at them close. This is the difference that tells the story, not the number of holes or the angle the back is cut at.

Look at the screw in the pin, does it have a roll pin going through it? Who made this stock kit? It is sometime possible to adjust the throw of the lever. By adding a shim under the lever, you decrease the depth of the holding pin. Some can even be screwed in to decrease the lock up detent.

I don't know how feeling the threads of the buffer tube is relevant to the stock...

the threads feels alright. a little cut off from the edge of the thread.

My problem is the lever.

as for the lever, i guess i will try to modify it somehow to work. i mean, why do i need to alter something, when i expected a product out of the box to be working properly how it should. now, am i right on this? to answer your question, this is the Magpul CTR full assembly Mil spec kit.

how unfortunate of me!

IGOTDIRT4U
02-03-2011, 11:42 AM
step 1.
Run your finger over the threads...are they RAISED or are they cut into tube? Look at them close. This is the difference that tells the story, not the number of holes or the angle the back is cut at.

Look at the screw in the pin, does it have a roll pin going through it? Who made this stock kit? It is sometime possible to adjust the throw of the lever. By adding a shim under the lever, you decrease the depth of the holding pin. Some can even be screwed in to decrease the lock up detent.


What I was thinking was the problem.

Echihn
02-03-2011, 4:13 PM
To comment on the 2 year old post about forging vs extruded... that is 100% not correct. Forging does not always make something stronger than extruded. In fact there are many cases where extruded parts will be much stronger than forged parts. It all depends on : the forging and extruding process, the types of metals and alloys used, the qc / tolerances, and many other variables. So bluntly saying forged is better than extruded is like saying diesel is better than gas. Both have a similar outcome (power in the case of my analogy of metals), and both have their pro's and cons, but when done right you can make a gas engine perform like a diesel, and you can make a diesel perform like a gas engine. They are just 2 diff ways to achieve an end goal.

Now, onto buffers, not all of them are hollow. It depends on the intended purpose, caliber round used etc. O and company that makes them. I have 3 buffers. One filled with flat round plates, and 2 solid ones. (my ar-57 buffer is a solid machined piece of metal).


Now, for the drillings on milspec vs commercial tubes... they should normally be the same. It will be the thread height and tube dimensions (along with the "rail" that keeps the stock vertical). The physical holes for stock positions should always be the same, regardless of tube.

A milspec stock should not fit on a commercial tube, but a commercial stock should fit on a milspec tube but with wobble.

Just because something is "milspec" doesn't mean it will have wobbles like mentioned.

This whole thread has dumbed me down with misinformation and more "opinions" on how things are made, well minus the 2 or 3 of you who know your stuff and posted good info.

Last off, this would be a little tip for newbies... but you should generally read the box before you toss it. It will say "milspec" or commercial on it. Now... depending on the quality of shop you buy stuff from, they could have pulled the stock and switched boxes for something that wasn't selling, or they could have a few on display and put them back into the wrong box, then sold to you. Either what this is not rocket science. Get a ruler and measure the inside diameter of the stock. It takes 2 seconds and literally a 5th grader could do it.