View Full Version : Mil-spec buffer tubes vs commercial
What is the difference between mil-spec tubes and regular? Does it make that much of a difference? Is it worth the money to switch out?
Riley~~~
Ridge_Runner_5
03-30-10, 19:31
Commercial tubes have a wider outer diameter.
Commercial stocks on a milspec tube will rattle.
Milspec stocks on a commercial tube will not fit.
The receiver extension is the part of the rifle, often mistakenly called the "buffer tube" that extends out from the back of the lower receiver. It not only holds the stock on the rifle but also does act as a tube for the buffer and bolt carrier to move back and forth inside of when the rifle cycles. This receiver extension is held in place by a castle nut which also holds the receiver end plate in plate, which in turn holds a spring and detent in place inside the lower.
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1.14" Diameter Receiver Extension
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This is often referred to as the "milspec" receiver extension. The alternative to a "milspec" receiver extension is the "civilian" or "commercial" receiver extension. There is some debate as to whether or not the milspec extension is actually stronger or "better" than the commercial, but for most users the real choice comes down to availability of aftermarket stocks. Some companies, like Magpul with their CTR stock, offer versions for both extensions, but many do not. If you know that your intended stock is available for the commercial receiver extension or if you are happy with the stock your rifle comes with it is most likely not an issue. If, however, you want to change the stock or just keep your options open then the milspec extension is preferred.
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Dimensions for a "milspec" receiver extension can be found here
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http://www.magpul.com/pdfs/buffertube-Milspec-M4.pdf
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Dimensions for a "commercial" receiver extension can be found here
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http://magpul.com/pdfs/buffertube-civilian-M4.pdf
Here's the link;
https://www.m4carbine.net/showthread.php?t=6642
I belive the commercial spec. is 1.17, I'd have to look it up to be certain but I belive this is it. Maybe someone else can confirm?
no reason to switch them as long as you have the right one on now.
The but end is also different between commercial and mil spec. Mil spec tubes will give you more choices for stocks if you're thinking about changing.
What is the difference between mil-spec tubes and regular? Does it make that much of a difference? Is it worth the money to switch out?
Riley~~~
It may make a difference if you find yourself bashing things often with the butt of your rifle, or if you feel you need to slam the butt on the ground for some reason. Otherwise, for just plain shooting, a commercial tube will suffice, as long as you are happy with the stock/stock options.
no reason to switch them as long as you have the right one on now.
I thought this was a brilliant comment, as it can be interpretted a number of different ways. And it made me laugh.
spamsammich
03-31-10, 12:03
https://www.m4carbine.net/showthread.php?t=7009
please familiarize yourself with the links provided above.
Doesn't commerical give you 4 postions between fully closed and fully opened......... and mil-spec give you 2?
So like 6 total vs 4 total.
Doesn't commerical give you 4 postions between fully closed and fully opened......... and mil-spec give you 2?
So like 6 total vs 4 total.
No, not at all. From the begining of collasping stocks to today you could probably find any number of combinations. I currently have a 6920 which, of course, has a mil-spec tube with 4 positions. I also have a LMT with Sopmod stock, which is a mil-spec tube and it has 6 positions. My last two Bushy's had commerical tubes and had 6 positions. I don't know the full history by any means, but I think the collasping stocks that began in the Viet Nam era only had 2 positions, fully closed and fully opened. Which gave way to 4 positions and now many have 6 positions on both mil-spec and commerical sizes. If anyone has more details please jump in.
ForTehNguyen
03-31-10, 15:52
when I had a commercial tube on one of my ARs, I swapped out to a milspec tube for $20, greater compatibility with aftermarket parts.
http://www.aimsurplus.com/product.aspx?item=XDSABuffer&groupid=57
MichaelZWilliamson
11-11-10, 14:53
I had an aluminum, GI-marked stock with three positions--open, 1" closed, fully closed. Total difference was only 2", so it was closer to "adjustable" than "collapsible" and didn't save any weight.
wolf_walker
11-11-10, 19:19
Mil tubes, or some of them, are made of stronger aluminum. Cheap mil tubes I've seen are the same cheaper alum as commercials are.
Code7inoaktown
11-11-10, 19:51
I thought the threads on the milspec were of a different gauge that was stronger than a commercial tube too?
This is relevant as well.
https://www.m4carbine.net/showthread.php?t=101&highlight=milspec+comercial+buffer+tube
wolf_walker
11-11-10, 19:58
I thought the threads on the milspec were of a different gauge that was stronger than a commercial tube too?
They are cut differently, but both fit the threads in the receiver.
Photo is worth a thousand words, basically the commercial tube is weaker aluminum that is easier to machine, and the threads are cut in a cheaper way. Lot more milling and strength on the mil tube. Not the end of the world having a commercial one, but the mil one is a nice touch no more than it costs in my opinion. And you might need to beat something to death with the stock one day, you never know. :)
PRGGodfather
11-11-10, 20:11
Extruded 6061 (cheap MilSpec "sized" receiver extensions are also Commercial 6061), vs. extruded 7075.
Translates to breaking strength of 45 vs. 75 lbs.
Thus, if 30 more lbs. of breaking strength is important to you, it's certainly worth the money. Seems like a good way to spend the additional $20-40 to me.
MichaelZWilliamson
11-11-10, 20:14
I'm always amazed at people who'll hang $1000 worth of accessories off a rifle, but think their trigger group, BCG and operating mechanism are "a waste of money."
I go with top end forgings, barrel and internals FIRST. Everything else can be changed as funds and style permit.
Extruded 6061 (cheap MilSpec "sized" receiver extensions are also Commercial 6061), vs. extruded 7075.
Translates to breaking strength of 45 vs. 75 lbs.
Thus, if 30 more lbs. of breaking strength is important to you, it's certainly worth the money. Seems like a good way to spend the additional $20-40 to me.
Is there a way easily tell which material it's made of?
I have a mil spec size tube and have always wondered...got it CHEAP so I doubt it's anything fantastic...would be nice to know, though.
PRGGodfather
11-11-10, 21:08
Unless you know the brand; nope, no easy way visually.
The correct 7075 MilSpec receiver extensions that I know of firsthand are from Bravo Company, Daniel Defense, Vltor and Colt. There are more, but I haven't played with all of them.
DSA makes MilSpec-sized receiver extensions for about $18-20, but they use extruded 6061. For many folks, this isn't a deal-killer, as 6061 is pretty sturdy stuff, and the ACE stocks are made of 6061, too; HOWEVER, please understand that the AR15 TDP was intended as the minimum for a fighting gun -- and the TDP calls for 7075 aluminum, forged or extruded.
7075 receiver extensions will often go for at least $45-50 (Vltor), with Colt being the most expensive at well over $100.
There are number of "assemblers" who will use the cheapest parts AR15 parts they can source and call it "MilSpec," with the intention of selling low and making a profit. That is a common business model, as the term "MilSpec" actually means little. For receiver extensions (AKA "buffer tubes"), the only things actually "MilSpec" is the overall size and outer dimensions.
In the firearms industry; however, marketing that low end model as reliable for self-defense is not the way many reputable folks want to do business. Quality isn't cheap, and cheap very often isn't quality.
You get for what you pay -- and when it comes to serious stuff, I like to think of it as cheap life insurance. If you want something inexpensive, perhaps the AR15 isn't the rifle on which to base your budget.
Still, this is America, and we are free to choose.
Be safe!
MichaelZWilliamson
11-11-10, 21:13
Who makes a modern 6 position to milspec? I know there are some out there somewhere.
Who makes a modern 6 position to milspec? I know there are some out there somewhere.
Bravo Company, VLTOR and I think Daniel Defense.
Who makes a modern 6 position to milspec? I know there are some out there somewhere.
I have BCM (Bravo Company) 6 pos extensions on my last 2 builds.
Wonder if CMT extensions are 7075. I have a few on builds from years ago, and checked into this a while back, but I have never heard for certain.
Wonder if CMT extensions are 7075.
Anybody know? :confused:
Found some relevant info that I have encountered previously on another forum:
http://www.weaponevolution.com/forum/showthread.php?2029-Mil-Spec-Buffer-Tubes&highlight=buffer
http://www.weaponevolution.com/forum/showthread.php?1559-Buffer-Tubes&p=25401
You may find this helpful:
https://www.m4carbine.net/showthread.php?t=18218
MichaelZWilliamson
12-11-10, 19:44
Bravo Company, VLTOR and I think Daniel Defense.
6 position length as well as number of holes? I like a long stock.
From what i can tell you guys say that the commercial and the milspec with thread in correctly. Is there anything else that you need to go from commercial to milspec? I have a DPMS and would like the milspec so i can transfer my butt stock for my rifle to my issued rifle when I want to. thanks
Extruded 6061 (cheap MilSpec "sized" receiver extensions are also Commercial 6061), vs. extruded 7075.
Translates to breaking strength of 45 vs. 75 lbs.
Thus, if 30 more lbs. of breaking strength is important to you, it's certainly worth the money. Seems like a good way to spend the additional $20-40 to me.
This.
From what i can tell you guys say that the commercial and the milspec with thread in correctly. Is there anything else that you need to go from commercial to milspec? I have a DPMS and would like the milspec so i can transfer my butt stock for my rifle to my issued rifle when I want to. thanks
If your asking will a standard mil spec receiver extension will fit into the dpms lower the answer is yes. The commercial stock will fit over a mil spec tube but it will rattle because the OD of a mil spec tube is smaller than commercial. If your asking because you would like to install a mil spec tube and stock, to at a later date, reinstall the commercial tube and stock the answer is yes, you can reinstall the commercial tube.
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If your asking will a standard mil spec receiver extension will fit into the dpms lower the answer is yes. The commercial stock will fit over a mil spec tube but it will rattle because the OD of a mil spec tube is smaller than commercial. If your asking because you would like to install a mil spec tube and stock, to at a later date, reinstall the commercial tube and stock the answer is yes, you can reinstall the commercial tube.
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I think after 5+ years, he's got it figured out. ;)
Doesn't mean someone else won't come across this same thread with the same question. A lot more newcomers in the AR world today than there was 5+ years ago.
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The last post prior to yours was from 2010.
Each post is date-stamped. Please make a habit of checking them out as you browse, and don't necro old threads unless you ass genuinely new information or have are asking a question not yet asked.
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