Lancer1 Posted May 23, 2014 Author Report Share Posted May 23, 2014 c'ntShtfish, the only other thing I can think of is the bolt stop/catch. Most lower parts kits will come with a standard bolt stop, the kind that goes in an AR 15. I had to research and realize that the bolt catch should be .308 specific. My bolt would hang back with the AR 15 catch, but it hung up on the follower, and eventually, I could not release the bolt after inserting a fresh mag. The chinsy one on the left in the picture is your AR15 bolt catch. The one on the right is a Bona Fide AR 10 bolt catch. DPMS also makes a .308 specific bolt catch, but it's in my rifle and I don't have a spare for photograh. Anyway, I ended up having to use the real mccoy, so I could release the bolt after firing the last shot in the magazine. It took me awhitle to get my hands on the actual, because like many other parts on these, the suppliers will say; "Oh, just use an AR 15 bolt catch". This was another fine point that I had to resolve, but once again, I learned much from it. You may get away with using the AR15, but my rifle is so picky, it will not function flawlessly, unless I have the exact, correct parts, LR 308 / AR 10 specific. Quote Link to comment Share on other sites More sharing options...
cantshootafish Posted July 30, 2014 Report Share Posted July 30, 2014 Thanks for the info Lancer1. I dug out the LPK and thank goodness I had bought the entire 308 kit from DPMS. It does have the correct bolt catch. Now I just have to find a good deal on an 18" barrel and adjustable gas block. The previous posting on magazines was quite interesting too. I already picked up 20 round pmags on sale a couple weeks ago, so things are starting to come together somewhat inexpensively. We sure do not have much selection for adjustable length stocks with this rifle length gas system and platform. Planning for weight saving is pretty much a waste of time. Quote Link to comment Share on other sites More sharing options...
Rsquared Posted July 30, 2014 Report Share Posted July 30, 2014 Uuhhhhh....Dude! There are many different stocks that you can put on these things. The gas system could care less about what kind of stock is on the rifle (or carbine). Magpuls, Ace, B5 (just to throw out a few) can all be fitted to the 308 platform. Quote Link to comment Share on other sites More sharing options...
Lancer1 Posted July 30, 2014 Author Report Share Posted July 30, 2014 Cantshootafish, as long as you have the correct buffer and spring for the .308, any configuration of butt stock will work. I have an A2 butt stock on one, and a collapsable M4 type on the other. I have put one of those MagPul type on there also, they all work. The tube diameter, and buffer diameter are the same, just make sure you have the right buffer / spring, as it is specific to the .308. There are lots of options, I bought my collapsable stock from Fulton Armory, those guys are reliable, and their parts are very high quality. Their "Titan" line of products are specific to the .308 platform. Quote Link to comment Share on other sites More sharing options...
cantshootafish Posted October 30, 2014 Report Share Posted October 30, 2014 OK. I ended up with a CMMG 18" barrel with rifle length gas for my DPMS based system. I just ordered the gas tube (which is all I need to complete this build) but everyone says (1) the same gas tubes are used for the .308 as the AR15, and everyone advertises their rifle length gas tube at 15.250 Previous lengths listed in this thread are 15.375 and the Armalite 15.50. Can anyone enlighten me to which is the correct length and if the AR15 and DPMS 308 are the same length tube? I called Brownells....and they were really confused. So much for their tech support.... Quote Link to comment Share on other sites More sharing options...
Lancer1 Posted October 30, 2014 Author Report Share Posted October 30, 2014 C-fish, read through this thread, I've tried to explain it in great detail. You have to do some fitting to realize which one you will need for your set up; if the regular ar15 gas tube fits far enough into the upper receiver, and it cycles corretly when fired, then you are good. If, like mine, it was 1/4 short (see my pictures), then you may need the Bona-fide Armalite gas tube which is 15-1/2" long. (some guys posted on this thread that they had a Fulton Armory barrel, and the regular ar 15 tube worked fine) (Well I'm talking about my rifle, not their rifles) I know it's an exhausting read, but even though I used a barrel from Fulton Armory, I had to pair it with an Armalite gas tube. The standard ar15 gas tube was just not long enough. If you turn your upper receiver upside down, look into it where the gas tube extends into it, there is a small inlet. I don't know the proper term for it, but the gas tube should reach half way into that inlet that I mention. Some guys just simply used the ar15 gas tube with no problem. I had to use the longer one, for it to work right. Did you look at the picutres I posted of the inside of the upper receiver? The gas tubes are the same diameter, it's just that the Armalite one, is about 1/4" longer. Quote Link to comment Share on other sites More sharing options...
Lancer1 Posted October 30, 2014 Author Report Share Posted October 30, 2014 C-fish, look at the very first frame, on the first page of this thread. You can see the picture I took of the the two upper receivers, and you can clearly see how one of the gas tubes is shorter than the other. So, in the rifle with the shorter one, I had to replace it (the gas tube) with the longer Armalite tube. Quote Link to comment Share on other sites More sharing options...
washguy Posted October 30, 2014 Report Share Posted October 30, 2014 Cantshoot since you have a CMMG the 15.25 regular ol rifle length tube should do the job...so yes an ar15 tube will work the problem was with the fulton of Lancers...and that particular barrel he has needed it...for whatever reason :) Wash Quote Link to comment Share on other sites More sharing options...
cantshootafish Posted November 1, 2014 Report Share Posted November 1, 2014 Thanks guys. It got even more confusing when looking at different sellers on fleabay since some were advertising their lengths at 15.125. Looking forward to finally getting this build finished. Quote Link to comment Share on other sites More sharing options...
cantshootafish Posted November 11, 2014 Report Share Posted November 11, 2014 Build done....rifle length gas tube works perfectly with DPMS style upper, lower and CMMG 18" barrel. Thanks too all for the info. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted November 11, 2014 Report Share Posted November 11, 2014 Thanks guys. It got even more confusing when looking at different sellers on fleabay since some were advertising their lengths at 15.125. Looking forward to finally getting this build finished. Buying rifle/gun parts on Fleabay will only lead to us diagnosing a bunch of crap later, when those parts fail or don't work at all. Please get your parts from a reputable firearms retailer or manufacturer. It saves all of us headaches. Quote Link to comment Share on other sites More sharing options...
cantshootafish Posted December 11, 2014 Report Share Posted December 11, 2014 I did. I just used ebay as an information source in their descriptions to show how things can get confused. Believe me though when I say that talking to the "experts" at Brownells did not yield any more valid information. The best info I got was from guys on this site. Quote Link to comment Share on other sites More sharing options...
washguy Posted December 11, 2014 Report Share Posted December 11, 2014 The only problem in over 22 plus years of messing with ar's is when I bought a new buffer tube off of ebay.... never ever again :) Wash Quote Link to comment Share on other sites More sharing options...
Lancer1 Posted January 31, 2015 Author Report Share Posted January 31, 2015 There's a lot of people on this forum that have FA barrels on there DPMS type rifles with rifle length gas system & have no problem with std AR 15 rifle length gas tubes , I have two of them myself . One a 20" & the other a 16" . There's more to this than saying all FA barrels need a AR 10 longer gas tube . Wonder if there are some mis matched or miss designated barrels made for FA. ? My barrels were made for a DPMS rife , what did , if any thing did they change ? Fulton Armory's web site (Jan 2015) now lists: Gas Tube, Rifle, FAR-308 AR, "Approximately .325" longer than AR-15 tube". There must be a reason for this. I must not have been the "Lone Ranger" with 308 gas tube length (AR-15 rifle length tube) issues on DPMS platform rifles. Someone else must have had the same problem. Otherwise, why would they change it? Quote Link to comment Share on other sites More sharing options...
moose-hunter Posted February 1, 2015 Report Share Posted February 1, 2015 Fulton Armory's web site (Jan 2015) now lists: Gas Tube, Rifle, FAR-308 AR, "Approximately .325" longer than AR-15 tube". There must be a reason for this. I must not have been the "Lone Ranger" with 308 gas tube length (AR-15 rifle length tube) issues on DPMS platform rifles. Someone else must have had the same problem. Otherwise, why would they change it? My Armalite tube measured 15.5". And a DPMS tube I had measured 15.125". Sounds like we now have a 3rd length with the FAR tube at 15.450". But... old eyes and small text on the rule coud negate the .050" difference. I too have a FA barrel... 18.5" with rifle length gas. The Armalite tube extends a full 1.00" inside the receiver (Mega Maten). so far, with only 30 or so rounds down the pipe, not one feeding issue. Can't say for sure if the DPMS tube would have caused short stroking on my build, but confidence is high that it would have. So... Why the "need" for the longer tube? Inquiring minds want to know. Quote Link to comment Share on other sites More sharing options...
mrmackc Posted February 1, 2015 Report Share Posted February 1, 2015 Lancet1, It is possible that the extractor let go of the cartridge rim because of the short gas tube rather than a weak extractor spring. On the DI gas system, part of the gas entering into the BCG pushes forward against the bolt to delay the bolt from opening before the pressure inside the cartridge case drops to a level to allow extraction. Your original extractor and spring may work fine with the new longer gas tube. Quote Link to comment Share on other sites More sharing options...
Lancer1 Posted February 1, 2015 Author Report Share Posted February 1, 2015 Well mrmackc, you might be right about that. I’m happy with the enhanced 5 coil extractor spring, and rubber “o” ring, so I see no reason to put the original back in. I’ve seen numerous .308 forum posts with extraction problems, so beefing up the claw and related components only serves to strengthen its function. This rifle performs flawlessly now. I’ve fired approximately 500 rounds through it in recent months, without a single failure of any kind. I’m building another one with a 24” Rainier Arms fluted barrel. After having to correct any kind of malady with my first two, I have a much better understanding of how the entire system works together. Fulton Armory sells those little extraction kits for a reason, and it seems to work perfectly in my two DPMS platform guns. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted February 1, 2015 Report Share Posted February 1, 2015 (edited) Fulton Armory's web site (Jan 2015) now lists: Gas Tube, Rifle, FAR-308 AR, "Approximately .325" longer than AR-15 tube". There must be a reason for this. I must not have been the "Lone Ranger" with 308 gas tube length (AR-15 rifle length tube) issues on DPMS platform rifles. Someone else must have had the same problem. Otherwise, why would they change it? I have two rifle length FA barrels with std AR 15 rifle length Gas Tubes & no problems. One on a DPMS Upper Receiver & the other on a Tactical Machining Upper receiver & also used a SI Defense Upper Receiver & none of them had any issues . I don't see it as an issue with the Gas Tube . I see it as another issue with no Standard for 308AR's . All Upper Receivers ( or Barrels ) not being to some sort of standard as compared to the MilSpec standard of the AR 15/M16/M4. Its why building an 308AR from some manufacturers, issues such as these come up & why building an 308AR can be a challenge with some configurations of different manufacturers components . Doesn't matter who made them of how well they are made . I have two DPMS Lower receivers with matching DPMS Uppers ( one a TM Upper ) & they work flawlessly , I have a early CMMG Lower & SI Defense Billet upper & that combo will not work reliably with the LR PMags , Any Steel mag works fine . This CMMG Billet Lower was made many years before the PMag was out , so I really can't blame CMMG , but it just goes to show , that all 308AR Parts or components don't play well together . The different length Gas tube at FA ,is probably just a AR 10 Tube , the measurements are just too close . There has been issues in the past where some using the AR 10 Gas tube, on a DPMS configuration, have had issues because its too long & switching to a std . AR 15 Gas Tube , fixed the problem , so you see it can get compacted building an 308 AR . The good thing is , its an inexpensive component to change out . You can blame the manufactures if you want , but it all comes down to , YOU , your building a Rifle , You made yourself a Hobbyist Gunsmith & stuff sometimes happens when building a Custom rifle <dontknow> Edited February 1, 2015 by survivalshop Quote Link to comment Share on other sites More sharing options...
Lancer1 Posted February 1, 2015 Author Report Share Posted February 1, 2015 Outstanding Survivalshop, well put! As I look back on the entire experience, at first I was frustrated because it (my first build) did not work like it should. Now, I am grateful for the challenge that came with LEARNING about how, and why components worked, or did not work. In my world, I'm an expert on how my own guns function, and can troubleshoot for myself if a malfunction arises. I'm not saying I'm an expert on LR-308 type rifles, just that my understanding of my own builds has made it possible to succeed, and to continue to build, and enjoy this platform. This journey has also led to handloading, so now I can craft my own .308 ammunition, safely and afford-ably. These rifles are superbly accurate, and really just a whole lot of good clean fun to shoot! The nice folks who participate on the 308AR.com forum make the endeavor even better with shared knowledge and help. What a great country this is (and I even live in California!) Quote Link to comment Share on other sites More sharing options...
98Z5V Posted February 3, 2015 Report Share Posted February 3, 2015 (edited) I know someone we can ask about this issue - seems like Fulton switched to the Armalite gas tube length for their barrel production, and the barrels would have to be built for that. Let's ask Josh, our Criterion Barrels sponsor... <thumbsup> EDIT - I started a new topic on it here: Edited February 3, 2015 by 98Z5V Quote Link to comment Share on other sites More sharing options...
Lancer1 Posted February 3, 2015 Author Report Share Posted February 3, 2015 Dang DEWS, 11,826 posts (?) (!) I'm going to go out a limb here, and say that you have contributed much to the collective here (and probably learned some things too!) <thumbsup> I don't have quite the networking capabilities that you do, but I did talk to Clint one time. I had a SA M1 Garand (CMP, circa 1943) restored by FA. He called me to confirm my order, and offer his expertise about my newly restored rifle. One of the many things he told me was, "Never use reloads in your M! Garand, or anyone else's". Thanks to you and all the other contributors for all the great content here. I never meant to complain about the FA barrel, or gas tube issue, it was all part of my educational journey! I'm a much improved AR 308 technician because of it. :auto: Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted February 3, 2015 Report Share Posted February 3, 2015 Don't give him too much credit. Half of those posts are smiley faces and pictures of his cat. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted February 3, 2015 Report Share Posted February 3, 2015 Don't give him too much credit. Half of those posts are smiley faces and pictures of his cat. Does that make him ,loquacious ? Just asking . <laughs> Quote Link to comment Share on other sites More sharing options...
mrmackc Posted February 3, 2015 Report Share Posted February 3, 2015 Does that make him ,loquacious ? Just asking . <laughs> Lo-what-isits. Is that one of Bill O'Really's words?.......splain that to this old Jarhead shooter, please Quote Link to comment Share on other sites More sharing options...
Rsquared Posted February 4, 2015 Report Share Posted February 4, 2015 Does that make him ,loquacious ? Just asking . <laughs> You've seen his post's haven't you? <lmao> 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.