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Posted: 12/18/2011 6:14:05 PM EDT
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I am planning on starting to do a custom build, but have a few questions.
I am aware there are Mil Spec and Commercial Buffer Tubes. With the Mil Spec Tubes being slightly larger in diameter than the Commercial, I was wondering if a Mil Spec Tube will fit the same lower as the Commercial Tube. I know the stocks are specific for the size tube, but I don't know if the Buffer Tubes are specific to special receivers. I would also like to know if there is a special tool needed to insert roll pins or just use a punch and tap them in. Any help would be greatly appreciated. 
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Not to be an ass, but the part is formally called a "receiver extension," which will help when you do your shopping. There are commercial and mil-spec carbine receiver extensions for collapsible stocks, but rifle extensions are all the same.
As noted, the commercial extensions are slightly larger in diameter due to the method of production. They are marginally less robust than mil-spec extensions in civilian applications, but I try to always go with the stronger option. |
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I would highly recommend the BCM mil-spec size 6 position carbine receiver extension, I have a couple of them and they seem to have a slightly larger diameter than other brands of mil-spec size receiver extensions.
All the mil-spec size buttstocks that I have like Colt M4, LMT M4, Vltor IMOD, EMOD, Magpul CTR & MOE fits snug with my BCM receiver extensions. If you don't have one already you would need to have an AR-15 carbine stock wrench, and I would recommend also staking the castle nut to prevent the tube from loosening. Ref: http://www.bravocompanyusa.com/Milspec-Receiver-Extension-Buffer-Tube-p/bcm%20milspec%20receiver%20extension.htm http://www.brownells.com/.aspx/pid=16882/Product/AR-15-M4-STOCK-WRENCH http://www.ar15.com/forums/t_3_118/387507_How_does_LMT_stake_the_castle_nut_.html http://cdn.magpul.com/downloads/Receiver_Extension_Comparison.pdf |
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Commercial or mil makes no difference as far as strength goes. The weakest point is the threads.
Stay away from airsoft crap and the bargain basement cheap stuff that flooded the market in the late80's and early 90's. That stuff still shows up on the secondary market. |
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Commercial or mil makes no difference as far as strength goes. The weakest point is the threads. Stay away from airsoft crap and the bargain basement cheap stuff that flooded the market in the late80's and early 90's. That stuff still shows up on the secondary market. Not necessarily, a mil-spec RE should be forged 7075 and many commercial RE's are extruded 6061. I see some manufacturers list their RE as "mil-spec diameter", that may mean they are not true mil-spec material. |
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My first rifle, and the one I still use the most, has a commercial tube. I've thought about changing it out, but I already have a stock I really like on it, it runs 100%, and if it ain't broke, don't fix it.
I'm building a "no corners cut" build, and was looking for something really good. I ordered the mil-spec receiver extension kit from LaRue, mainly because of the spring. I assume their tube and buffer are top-notch, too. I was also just looking for a reason to order from them, as I had started this project with my heart set on an OBR, but then ran on to a great deal on a Noveske upper. Will someone in the know tell me if it was a waste of money, or if I'll really be that much better off with the LaRue buffer tube set-up? (for the record, I'm going to use the Spike's enhanced LPK, and a SuperiorArms stripped lower, Troy BUIS, Aimpoint PRO in LaRue mount, Flaming Pig up front) |
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My first rifle, and the one I still use the most, has a commercial tube. I've thought about changing it out, but I already have a stock I really like on it, it runs 100%, and if it ain't broke, don't fix it. I'm building a "no corners cut" build, and was looking for something really good. I ordered the mil-spec receiver extension kit from LaRue, mainly because of the spring. I assume their tube and buffer are top-notch, too. I was also just looking for a reason to order from them, as I had started this project with my heart set on an OBR, but then ran on to a great deal on a Noveske upper. Will someone in the know tell me if it was a waste of money, or if I'll really be that much better off with the LaRue buffer tube set-up? (for the record, I'm going to use the Spike's enhanced LPK, and a SuperiorArms stripped lower, Troy BUIS, Aimpoint PRO in LaRue mount, Flaming Pig up front) The receiver extension in the kit is not made in-house. I'm sure it is good quality as you could expect anything you'd buy from LaRue would be. They sell their in-house manufactured receiver extension separately on the website. I'm about to order a couple.  Posted Via AR15.Com Mobile |
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I'm building a "no corners cut" build, and was looking for something really good. I ordered the mil-spec receiver extension kit from LaRue, mainly because of the spring. I assume their tube and buffer are top-notch, too. I was also just looking for a reason to order from them, as I had started this project with my heart set on an OBR, but then ran on to a great deal on a Noveske upper. Will someone in the know tell me if it was a waste of money, or if I'll really be that much better off with the LaRue buffer tube set-up? The LaRue mil-spec RE kit have excellent quality, I got one last year which I also ordered a Magpul MOE stock with it, it's mounted on a heavy recoiling 7.62X39mm cal. 16" HBAR carbine, I'm very satisfied with it. |
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Not to be an ass, but the part is formally called a "receiver extension," which will help when you do your shopping. There are commercial and mil-spec carbine receiver extensions for collapsible stocks, but rifle extensions are all the same. As noted, the commercial extensions are slightly larger in diameter due to the method of production. They are marginally less robust than mil-spec extensions in civilian applications, but I try to always go with the stronger option. To complicate matters a bit further, Vltor makes the A5 receiver extension which uses a collapsible stock and a rifle-length buffer. |
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Quoted: To complicate matters a bit further, Vltor makes the A5 receiver extension which uses a collapsible stock and a rifle-length buffer. I just built a new lower with the Vltor A5 system. I say system because there is specific A5 spring and A5 buffer (actually a couple) that go along with it. On this, I am specifically using it for a 3 Gun setup to mitigate recoil. |
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Commercial or mil makes no difference as far as strength goes. The weakest point is the threads. Stay away from airsoft crap and the bargain basement cheap stuff that flooded the market in the late80's and early 90's. That stuff still shows up on the secondary market. Not necessarily, a mil-spec RE should be forged 7075 and many commercial RE's are extruded 6061. I see some manufacturers list their RE as "mil-spec diameter", that may mean they are not true mil-spec material. Unfortunately not. Both are extrusions. Commercial tubes take less machine work to make. Less machine work is more units per man/machine hour and less wear on the cutting tools. The myth of milspec being forged continues for some reason. Here's a link to the M4 Milspec |
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To complicate matters a bit further, Vltor makes the A5 receiver extension which uses a collapsible stock and a rifle-length buffer. I just built a new lower with the Vltor A5 system. I say system because there is specific A5 spring and A5 buffer (actually a couple) that go along with it. On this, I am specifically using it for a 3 Gun setup to mitigate recoil. I was under the impression that the A5 extension used a normal rifle action spring and rifle buffer? |
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Would you be so kind as to point us to a specific page and paragraph that calls out manufacturing method in the document for which you posted a link? GSM Mil-SPECs do not include dimensions, methods, etc., just how the parts and final product are measured for compliance. I've read elsewhere that MIL extensions are made by a process that holds a blank of metal in a form and rams a punch into it, creating the basic inner and outer shape and rough dimensions through a kind of forging process. Can't find the reference right now. In contrast, commercial extensions are typically drawn. Ramming into the material is inherently a forging-like process, while drawing is a "pulling" process-they're very different, and the internal metal structure resulting from the two processes is inherently very different. |
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I believe this is the method for making mil-spec tubes.
impact extrusion |
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To complicate matters a bit further, Vltor makes the A5 receiver extension which uses a collapsible stock and a rifle-length buffer. I just built a new lower with the Vltor A5 system. I say system because there is specific A5 spring and A5 buffer (actually a couple) that go along with it. On this, I am specifically using it for a 3 Gun setup to mitigate recoil. I was under the impression that the A5 extension used a normal rifle action spring and rifle buffer? I derped. According to the A5 page, it's a rifle-length spring but a special A5 buffer. |
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That's my understanding, though I wish I could find my sources to cite them. |
| Back to the OP's post. I believe the extension has been covered enough. Roll pins. Needle nose pliers are handy to start them or you could get the roll pin starter tool, I've never needed it but to each their own. A punch and of course a small hammer. I prefer brass. A tip on the roll pins, freeze them the night before. If you work fast they go in pretty easily. YMMV. |
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