Lancer1

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:

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!)

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.

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?

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.

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.

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.

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.

Outstanding. I'm glad you got it to work. And, if you are happy with it, that's all that matters !

dingdong, look at you, you got it to work <thumbsup>. Clean that thing up and run the bolt/carrier nice and lubed up (I even used Mobile ONE)( I read that I should use grease on exposed sliding parts, and oil in confined areas, so it doesn't sling out). What about the extractor, could it be letting go of the empty brass too soon after it gets jerked out of the chamber? (if so, the empty case just lays there/bounces around in the chamber/magazine area, and interferes with the incoming round) With the Federal Bonded ammo, did you check to see if the bolt will hang open on an empty magazine? (just load one round in the mag, then shoot, see if the bolt carrier hangs back) Even though I had paid like $265 for a JP Enhanced bolt, I had to replace the extractor spring, and add the little rubber o ring (around the spring) to stiffen it up. (Extractor spring, 4 coil (no good), 5 coil spring (Fulton Armory), worked good!). I kept chipping away at all these quirks, now it shoots any ammunition I put in it. I also put an adjustable gas block on there, but I left it wide open (full charge). It really slams the bolt back hard (although there is not much felt recoil), I almost thought it was "over gassed", but no, it cycles like it should. Please don't stop checking on all these issues, I had to go to the range like 5 times before I got ALL the kinks out. It should really cycle with any appropriate ammunition. 165gr Federal Bonded included. It should also loosen up as you shoot 200, 300 rounds. What say you Double D?

I did not intend to say that "all" FA barrels on DPMS type rifles need an AR 10 gas tube. If I said that, then I need to be more articulate when posting. All I'm saying is "MY" FA barrel required the use of the longer, AR 10 gas tube for it to function correctly. With the standard AR 15 rifle length tube, I realized that the bolt would not hold open on an empty magazine. So, after I put the ArmaLite gas tube in, the bolt carrier held back by the bolt catch, as it is supposed to do. In my case, would you not agree that this is an indicator? This circumstance led me to understand that the bolt carrier was not being sent back far enough to engage the bolt catch / hang on the empty magazine (with standard gas tube installed). I'm happy for everyone that has a DPMS type rifle, with a FA barrel, and use a standard AR 15 rifle length gas tube. I notice that FA no longer offers the 22" barrel for sale. I notice that I was not the only person to have trouble with insufficient (under gassing) pressure to throw the bolt carrier back far enough (and I have the correct buffer, and spring). Also, I could plainly see that the two gas tubes did not extend into the upper receiver equally. Step by step, I was able to find out why my rifle did not function correctly, and now it does. I've seen many times on this site (good advise) to check and see if the bolt carrier is held back on an empty magazine, because that is an indicator.

Well what do you know? The barrel that I put on my "DPMS" platform upper receiver, was indeed from Fulton Armory. And it would not work with a regular rifle length gas tube, I had to hunt down an ArmaLite rifle length gas tube to get it to work right. The barrel shoots deadly accurately, it is stainless steel, 22". I'm happy with the barrel, it just took me some research and time to figure all that out. This all makes sense. I wonder where the difference lies, is it in the barrel extension? Or is the length from the breech to the gas block (where the gas port is) longer than a barrel made for a DPMS rifle? Your conversation with the folks a Criterion would have been of special interest to me while I was wondering why I had stove pipes, failure to feeds. I really started to figure it out from someone on this site, he said something like "how far into the upper receiver should the gas tube reach". Then I started to look at my other DPMS (the one that works), and I noticed that the gas tube I had on the FA barrel only went it about half as far as the other one (other DPMS upper). Anyway, look at the pictures I posted and you can see the difference in how far the tube reaches into the upper receiver. Don't forget to make sure your extractor spring is stout enough (five coil, also from FA), and also to put that little black "O" ring over the extractor spring. That was part of my problem. The extractor was letting go of the empty case too soon, and the bolt went all the way back, picked up another round, and tried to cram it into the chamber along with the dropped empty (stove pipe). These things are a bit finicky, don't let it beat you down, keep trying because when everything works like it should, it is a beautiful thing. I have an MIA, M1 Garand, 3 AR-15's, and two LR-308's (clone). I think the DPMS type 308 with the FA barrel on it is my favorite shooter out of all of them. Something else that makes it my favorite is being able to handload for it. 168 gran HPBT's, over Varget, or W 748, or a number of other powders, really brings out the "MOA" on it.

Dingdong, that' funny (it sucks) that they replied to you, and not me. I sent them numerous emails about them sending me the wrong part, they never did reply. I would check with DSG arms, they are an ArmaLite distributor, and they were right on the money with this gas tube (and their technician new the difference in gas tube lengths). It fixed my problem. See if DSG has it in stock, don't even mess with Delta3 if you don't have to. It took me a few months to get all the kinks out of that build, now it works flawlessly, and I would trust that gun in combat. I had to do extensive research, I changed the extractor spring, and also put an adjustable gas block on there. Finally, I got it to work as the design is intended. Please let me know if I can be of any help with your issues. Actually, I finally got one from ArmaLite (actual), it was on backorder from them, but they finally sent it to me. Now I have two of them, plus the other one that is too short. Anyway, let me know if I can provide anything else to help.

Photon, only the rifle length gas tubes are different. A bona fide ArmaLIte rifle length gas tube will be 15-1/2 inches long. The DPMS LR 308 platform (rifle length) will use a standard AR 15 rifle gas tube which is 15-3/8" long. Even though all my parts were advertised as DPMS compatible, the 22" barrel I got from Fulton Armory had to have the actual ArmaLite rifle length gas tube. I understand you are not concered with the rifle length, but just make sure everything fits correctly, or you may have Failure to Feed, Failure to Eject problems. Also, I had to install the stiffer 5 coil extractor spring, and the rubber o-ring in my bolt carrier. The standard spring would not hold on to the brass hard enough to extract/eject the fired brass. You may have some tweeking to do with any build. These 308 AR type rifles are dealing with a lot more pressure than the 5.56 rifles, so there is more opportunity for problems.

OK, I meant that for Wraith 1967, not Robocop. With regard to Robocop's statement, the real ArmaLite AR-10 rifle (rifle length gas system) uses a 15-1/2" long gas tube. This is right from the ArmaLite technichians from their factory. The DPMS platform can use any AR 15 type gas tube - 15-3/8" long. (Rifle Length gas tube system). My LR 308 clone that I built with a Fulton Armory barrel, had to have the actual ArmaLite gas tube, as the AR 15 gas tube would not reach far enough into the upper receiver to engage the gas key. So, for Wraith 1967, I got my 15-1/2" gas tube from DSG arms.

Robocop1051, I got my (authentic ArmaLite Rifle length gas tube - 15-1/2 inches long) from a website called DSG Arms. They have the real mcoy, and I also got one from Armalite itself. I bought one from a place called Delta 3 tacticle (advertised as an ArmaLity part), but it was not a real ArmaLite rifle length gas tube, as it was only 15 - 3/8, which is a standard AR 15 rifle length. That one was no good to me, and I complained to Delta 3, but they would not respond. Anyway, the actual, no-S#@% Armalite tube is what I needed, and now my rifle works like it is supposed to.

My 308 build problem has come to be resolved. I installed the actual ArmaLite 308 gas tube which is actually 15 -1/2" long. I installed an upgrade to the extractor from Fulton Armory, along with the stiffer extractor spring (5 coil), the poly insert, and the rubber O ring. I installed the Timney 4 LB trigger, and a JP adjustable gas block. I replaced the weeping DPMS magazines with KAC 10 round mags. This rifle has been a great learning experience for me. I built it from an assemblage of parts, and you really have to fine tune it to get it working properly. This thing functions flawlessly, and is deadly accurate. No more stove pipe / feeding / ejection issues. The gas tube now reaches all the way into the bolt carrier key, and imparts a full gas charge. The new magazines feed correctly. The Fulton Armory 22" Stainless Bull barrel is an absolute tack driver. Even though this California legal rifle is impaired with the required bullet button, it is now a trusted, and favorite gun. Thanks to all for the inputs and discussion. The internet and 308AR.com are wonderful things!

Dang, I'm having a heck of a time trying to resolve this. I received a gas tube advertised with the correct part number (10007010) from a place called Delta 3, but it is not 15 - 1/2" long. The technicians at ArmaLite have confirmed that the actual ArmaLite AR 10 gas tube is indeed 15 - 1/2". Delta 3 must have sent me the M-15 gas tube which is 15 - 3/16", so it is not long enough. ArmaLite took my order for the original, but it is back ordered with the arrival being unknown. This sticking point has brought me to a halt with my 22" Fulton Armory built rifle. "The Devil is in the Details"! Fortunately I have another complete rifle that works like it should, and I just put a Timney trigger in there. It has an 18" barrel, and shoots really straight. But I really wanted to blast that 22" stainless barrel this week. I just have to be patient, and wait!

Jgun, I'll take your advise about making sure the gas key doesn't bottom out with the longer gas tube in there. I should get the AR-10 gas tube tomorrow in the mail. I've learned alot about .308 magazines trying to fix this. The actual DPMS 10 mags suck! PRO Mag 10's work good, ASC mags work good and these are relatively inexpensive. The really nice ones are the actual KAC, they are beautifully made (tig welded), but cost $124 (the only KAC's I could find). Magpul 20 round (modified to block them to 10 because I'm in California) seem good, I will shoot them this week. I will post the results of the AR 10 gas tube when I get my hands on it. Thanks for your input.

Jgun, both of the rifles in that picture have the standard, AR15 Rifle length gas tubes (15-1/8"). The bright stainless barrel's gas tube is the one I need to change because the standard gas tube does not reach far enough into the upper receiver, and I think that's why I'm not getting enough blowback on the bolt carrier. I cannot push the gas block any farther reward, as it butts up against the shoulder on the barrel. Either the barrel extension on that barrel is longer, or the shoulder where the gas block butts up against it (and the gas port) is 3/8" farther forward towards the muzzel. Whatever creates this 3/8 inch difference, I'm not sure. Both gas tubes are the same length. This is why I have ordered an Armalite AR-10 gas tube, because it is 15-1/2" long, and I'm hoping it will fit in a standard gas block. The extra 3/8" length of the Armalite rifle length gas tube should make up the difference, and extend into the upper receiver to where it should be. The bolt carrier closes into battery in both uppers, so if the Armalite gas tube fits into the upper as it should, both of my gas tubes will extend into the receivers to the same length. Thus, I should get a full charge of gas, pushing my BCG back far enough. I have even purchased a JP adjustable gas block so I can "turn it down" if I'm getting over pressure. What do you think?

Yes Imschur, I did see it. The SASS stands for Semi Automatic Sniper System, right? Does that have to do with the length of the gas tube? I originally thought the the gas tubes were standard AR 15 rifle length gas tubes if used on DPMS type rifles. I guess I don't know the specifics of the SASS gas blocks. Do they have different dimensions?

OK, I guess it would not be the barrel nut, but perhaps the barrel extension / flange as survivalshop points out.

No worries Edgecrusher, I'm sorry I misinterpreted your coment. From reading here, I realized that I didn't think of everything. For example, it did not dawn on me until now that the barrel nuts could differ in length, or even the barrel extention (thanks survivalshop). It's just a wake up call that when you build these rifles, you have to check everything (all components) to enusre they come together as the DPMS platform requires for everything to work. Thanks to everyone for the inputs.

Yes, the gas blocks are different. However, both of them fit directly over the gas ports in both barrels. The JP hand gard would be difficult to remove because it calls for thread lock, and I would have to heat it with a torch to take it off. I suppose it might also be caused by the barrel nuts, if there is a difference in how long they are. I didn't check that. I hope the diamiter of the AR 10 gas tube is the same, so it will fit in the hole on the gas block. If I can pin the AR 10 gas tube into the gas block, the added lenth of it should extend it to where it should be to meet the carrier key.

OK, I did not post here to be ridiculed. I was looking for constructive advice on why the gas port on a Fulton Armory barrel might be 3/8" farther forward, because it does not extend into the upper receiver as far as the other one (the other one works, feeds, etc..). Forgive my ingnorance, it was not my intention to irritate or amuse.