survivalshop Posted July 22, 2012 Report Share Posted July 22, 2012 I was not sure where to put this , since its for all AR types . I found a rec. ext. that is kinda odd , I talked about it in the Black rifle thread , in the pinky post by 98. Check these photo's ,both of these are mil spec out side dia. tubes ,but that's where they stop.The true Mil spec one is aprox. 7 3/16 long & the other wanna be is 7 13/16 long & have the std commercial tail on it , a dead give away ,but is being sold as a true Mil spec.Thread size or type are not mil spec ether. Quote Link to comment Share on other sites More sharing options...
unforgiven Posted July 22, 2012 Report Share Posted July 22, 2012 Hard to tell but the tread pitch seems the same <dontknow>Where does the oddball belong? Quote Link to comment Share on other sites More sharing options...
Jgun Posted July 22, 2012 Report Share Posted July 22, 2012 I have no ID info to offer on this, but, if the outside measures the same, aside from the length, and the bore dia is also OK, my question to you is, if the knock off is 5/8" longer outside, is it also the same amount longer inside? What had occured to me was that depending on the answer to my question, the longer extension might be useful for changing the way that a gun cycles? Even if the ID matched the mil spec tube, if the extra length on the knock of is between the first stock adjustment hole and the receiver, your picking up an extra 5/8" of LOP at every position. Might be a useful thing to fine tune your collapsing stock, not to mention the possibility of playing with the cycling of the carrier, by adding or subtracting length inside with spacers, if in fact the bore is 5/8" deeper as the OAL is longer. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted July 22, 2012 Report Share Posted July 22, 2012 ss, is this extension from the VLTOR A5 setup?http://www.vltor.com/emod-a5.html Quote Link to comment Share on other sites More sharing options...
survivalshop Posted July 22, 2012 Author Report Share Posted July 22, 2012 ss, is this extension from the VLTOR A5 setup?http://www.vltor.com/emod-a5.htmlNot a Vltor, I know that for sure . I'm not absolutely sure who made it ( I have an idea but will not name a name because I really don't know & of course there is not a manufacturers name on it ) , but I get 90% of my AR parts from one place & its not there fault , I picked this out myself , because it read mil spec until I got to looking at it. It is mil spec tube dia & that's where it ends . I installed it on a customers rifle & that's when I really noticed it didn't look right . Had to order a real mil spec one .I have a the install instructions from one of my older CTR stacks & it gives all the dimensions of the two receiver extensions & as said it has the mil spec tube dia. but the length & thread dia are commercial .Mil spec thread dia ------1.185"commercial thread dia---1.170" If you guys want me to scan these instructions , which have a good drawings & measurements , I will .I could not find it quickly on there web sight. And yes a mil spec CTR went on this extension with no problem & fits good .If we don't have this info on the sight , here it is. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted July 22, 2012 Report Share Posted July 22, 2012 Mil spec thread dia ------1.185"commercial thread dia---1.170" Milspec diameter is 1.14", man, not 1.185" - if that tube is 1.185" that you've got, it's looking like an oversized commercial extension. Quote Link to comment Share on other sites More sharing options...
Jgun Posted July 22, 2012 Report Share Posted July 22, 2012 Maybe you guys can clarify this for me. I see in the drawing, (and I was under the impression that it was true) that both the mil spec and commercial tubes share the same 1 3/16"-16 thread that attaches them to the lower. After all, there is only one thread specefied in all of the lowers, right? If this is so, the 1.170" and 1.185 " refer to the OD of the tube behind the thread, where the collapsing stock slides on, no? Am I also correct in understanding that all of them are supposed to have the same inside dia, since I've never seen a buffer refered to as mil spec or commercial. Unless I've gotten some of the above wrong isn't the only difference between the two supposed to be the outside dia, and maybe the OAL? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted July 22, 2012 Report Share Posted July 22, 2012 Correct, with the above, minus one thing - the OAL. Inside OAL has to be the same, and outer OAL should be the same, also. The only things (besides material, 6061 or 7075 aluminum) that should differ are the outside diameter, 1.14" or 1.17", and how they form/cut the threads.The VLTOR A5 system is the obvious exception. Quote Link to comment Share on other sites More sharing options...
Jgun Posted July 22, 2012 Report Share Posted July 22, 2012 So, if SS has a tube that is 5/8" longer than a standard carbine tube, aside from the possible added LOP, I wonder what that extra buffer travel could do do for you? maybe slow down cycling which might aid in ejection? Or maybe you might have issues with the gun not having as much energy to load the rd and lock the bolt. Sounds as though it might be a fun part to play around with. Survivalshop, if you decide you don't want it because it's out of spec, and your not interesteed in experimenting with it, I'd be interested in buying it from you to see what it does in one of my AR's Quote Link to comment Share on other sites More sharing options...
98Z5V Posted July 22, 2012 Report Share Posted July 22, 2012 There's something different about RRA .308 carbine extensions - I'm wondering if it's one of those, since it's not the VLTOR A5... <dontknow>If it's 5/8" longer internally, and your buffer is going back another 5/8" with every stroke, it's gonna SLAM into your bolt catch on an empty mag. Hard. Quote Link to comment Share on other sites More sharing options...
Jgun Posted July 23, 2012 Report Share Posted July 23, 2012 I hadn't considered the bolt catch, I wonder what could be done to reduce that, I wonder if an extra power, or slightly longer spring, might reduce some of that extra travel? I wonder if a stronger spring might keep it from traveling the full 5/8" further back? I guess this warrants further thought, that is, if he decides that he doesn't want the tube. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted July 23, 2012 Report Share Posted July 23, 2012 The extra 5/8" of travel - if that tube is indeed 5/8" extra internal length, too - is nothing good. There's nothing that you can do with that extra travel, to use to your advantage, or to make anything good come of it. That wll tear a gun up quick. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted July 23, 2012 Report Share Posted July 23, 2012 From Slash's page on the CAR-10 buffer (for .308's):Note: This buffer is designed for use in .308 ARs with a 7" receiver extension (buffer tube). If you have an ArmaLite/VLTOR extended length tube (7-3/4") please see the AR15 Carbine Buffer page. Not compatible with .223 ARs. This thing that ss has is not a standard AR-15 carbine receiver extension. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted July 24, 2012 Author Report Share Posted July 24, 2012 Milspec diameter is 1.14", man, not 1.185" - if that tube is 1.185" that you've got, it's looking like an oversized commercial extension.If you look at the drawing & my post , its the out side thread dia . , not the out side extension tube dia . . The extra length , IMO , as said by 98 , is not a good thing , it reduces the spring compression & may cause BCG over travel . I can not tell you if this extension worked or not firing , but did work in hand cycling the action.Contrary to popular INTERNET belief , all receiver extensions are made from extruded 6061 , if you wanted one made with forged 7075 as is popularly believed , it would cost as much as a receiver set .I finally got a manufacturer to admit it on another sight . Now the threads are another thing , mil spec's are rolled & commercial are die cut , that's why they look different & why mil spec fit better. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted July 24, 2012 Author Report Share Posted July 24, 2012 From Slash's page on the CAR-10 buffer (for .308's):Note: This buffer is designed for use in .308 ARs with a 7" receiver extension (buffer tube). If you have an ArmaLite/VLTOR extended length tube (7-3/4") please see the AR15 Carbine Buffer page. Not compatible with .223 ARs. This thing that ss has is not a standard AR-15 carbine receiver extension.Thats for sure , but I have a Commercial extension on my 16" 308 & will pull the CTR off & check it out . Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.