Alamo Posted May 23, 2014 Report Share Posted May 23, 2014 Hello everybody, Recently bought a new Sportical .308 and had put about 50 or so rounds through it. I installed some iron sights, using the gas block rail for the front sight and subsequently noticed that the gas block would wiggle back and forth. At first I thought it was just not tightened down properly, but after loosening the gas block screws and pulling the gas tube out of the upper receiver, I was able to unscrew the entire barrel by hand! (it was threaded onto the barrel extension) I'm far from an expert on AR pattern rifles, but this seems to me to be highly irregular. The way it's put together isn't something I've seen before or been able to find on the Internet. Unlike most barrels assemblies, there is no pin and the barrel nut doesn't hold the barrel on at all. The nut holds the barrel extension to the upper receiver, but the only thing holding the barrel to the extension are those threads on the barrel. I took it to my local gunsmith and he also had never seen anything like it. He put the barrel back on and tightened it down, re-installed and aligned the gas block/ tube and checked the headspace to make sure it was still OK. I took it back to the range and 50 rounds later it's loose again. I just don't see any way that the barrel can stay on given the lack of some sort of washer or a pin or something to keep it from unwinding every time it gets shot. My gunsmith is more of an AK/ FAL type of guy (though he does work on AR pattern rifles, but he's kind of an "arteeest", says he likes to do more "challenging" builds)... so I wanted to put it in front of the experts on AR .308 rifles. Is this something you guys have seen before? Is this type of assembly flawed or is there a fix? Any assistance is much appreciated. Quote Link to comment Share on other sites More sharing options...
planeflyer21 Posted May 23, 2014 Report Share Posted May 23, 2014 Welcome aboard, Alamo! We usually see these questions in the CMMG threads. If the gunsmith torqued the barrel nut correctly, I have a hard time seeing why it would shoot loose again. Got pics? Quote Link to comment Share on other sites More sharing options...
Alamo Posted May 23, 2014 Author Report Share Posted May 23, 2014 Thanks for the reply & welcome plane flyer. I thought the same thing at 1st, until I took it apart. The barrel nut is still tight as can be, but there's no flange on the barrel that the nut fits over. I've included a pic. Quote Link to comment Share on other sites More sharing options...
unforgiven Posted May 23, 2014 Report Share Posted May 23, 2014 Welcome from Indiana brother Alamo,someone here has an answer.You are caller #5...enjoy the muzak. ^-^ Quote Link to comment Share on other sites More sharing options...
FaRKle! Posted May 23, 2014 Report Share Posted May 23, 2014 Wow the barrel came loose from the barrel extension? You can't fix that on your own, and and that whole barrel needs to be replaced. Quote Link to comment Share on other sites More sharing options...
Alamo Posted May 23, 2014 Author Report Share Posted May 23, 2014 (edited) Thanks guys. Yeah, I figured as much. Even if I sent it back to DPMS, I don't know how they would get it to stay on with the barrel threaded onto the extension the way it is without any mechanism to prevent the threads from loosening under stress. I'm thinking about switching it out for an 18" SASS barrel... but that's another thread. In doing all this research into what's going on with the barrel, I've been bitten by some sort of bug and caught some sort of fever... anybody here have any experience with that? Edited May 23, 2014 by Alamo Quote Link to comment Share on other sites More sharing options...
Rsquared Posted May 23, 2014 Report Share Posted May 23, 2014 Yep. It's widespread. And we all have it. That's why we're here. Quote Link to comment Share on other sites More sharing options...
unforgiven Posted May 23, 2014 Report Share Posted May 23, 2014 It's 12 steps in reverse,cause you only get more broke. <lmao> Quote Link to comment Share on other sites More sharing options...
Alamo Posted May 23, 2014 Author Report Share Posted May 23, 2014 I get it, kind of like a country song... only you get to keep your rifle. Quote Link to comment Share on other sites More sharing options...
planeflyer21 Posted May 23, 2014 Report Share Posted May 23, 2014 Just a word though on DPMS's customer service. OUTSTANDING!! You don't have a thing to worry about. Give them a call, tell them what's up and they should send you a shipping label on their dime. Quote Link to comment Share on other sites More sharing options...
Alamo Posted May 23, 2014 Author Report Share Posted May 23, 2014 (edited) I will definitely give them a call if I decide to keep using that same barrel. However, after my initial use of the rifle, there are a few things I'd like to change/ improve: 1. If I don't release the charging handle cleanly, the bolt doesn't go into full battery. Since there is no forward assist, I would try pulling the charging handle back a little and re-releasing... sometimes it would work & sometimes it would push another round in under the one already chambered. Possibly a break-in issue that would clear up after some use, possibly a training issue that would clear up after some practice. Regardless, I've decided that this is fine for a bench rest rifle, but it isn't an issue I want present on a tactical rifle. Solution: change uppers to one with the built in FA and ejection port cover. 2. I want a slightly longer, more accurate barrel. Probably this one: DPMS SASS Barrel LR-308 308 Winchester Bull Contour 1 in 10" Twist 18" Fluted Stainless Steel Black Teflon 3. The gas block rail is not on the same level as the upper rail (upper is HP, rail is for the newer LP rail upper). I'd like to add a Troy TRX Extreme Battle Rail to match the new LP upper with FA & dust cover. I'm sure I'll come up with additional stuff as well as need answers to assorted questions/ complications associated with changing the stock parts. Once I get a better handle on what I want to do, I'll post another thread with the build questions. Edited May 23, 2014 by Alamo Quote Link to comment Share on other sites More sharing options...
gnatshooter Posted May 23, 2014 Report Share Posted May 23, 2014 If I don't release the charging handle cleanly, the bolt doesn't go into full battery. Since there is no forward assist, I would try pulling the charging handle back a little and re-releasing... sometimes it would work & sometimes it would push another round in under the one already chambered. . I had the same problem with my DPMS LR-308T with the slick-sided high-profile upper, but I could solve the problem of not going into full battery by pushing forward on the charging handle. But now, after things are more broken in, the bolt always goes into full battery no matter how gently and slowly I ease it forward. I've since switched to a low-profile upper receiver and it has a forward assist that I don't think I will ever need. Quote Link to comment Share on other sites More sharing options...
Alamo Posted May 23, 2014 Author Report Share Posted May 23, 2014 Thanks gnatshooter, good to know. I guess I'll keep the original upper around until it evens out a bit. Your handle reminds me of a scene from the movie, "They Call Me Bruce": "You see that fly?" (slices at fly with Samurai sword and the fly flies away) "You missed" "Ahh, but that fly will never make love again" Quote Link to comment Share on other sites More sharing options...
FaRKle! Posted May 23, 2014 Report Share Posted May 23, 2014 1. If I don't release the charging handle cleanly, the bolt doesn't go into full battery. Since there is no forward assist...Stoner's original design didn't have a FA either. Ever wonder why there's that indentation in the BCG just behind the forward gas holes on the carrier? So your finger can push the bolt into battery if you need to. Quote Link to comment Share on other sites More sharing options...
Alamo Posted May 23, 2014 Author Report Share Posted May 23, 2014 Thanks Farkle, good advice. Improve the user... rather than just the device. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted May 23, 2014 Report Share Posted May 23, 2014 If its a factory rifle with all the OEM parts on it , the way it came , DPMS should replace the barrel. When changing the gas block , was a Muzzle device removed to replace the gas block & if so , how was it removed ? If the barrel was not supported & locked down with Vice Blocks & that's not an upper receiver block , chances are if you had a tight Muzzle device , the barrel can be unscrewed from the Barrel extension. Put it back to original configuration if you can & talk to DPMS. The fact that its coming loose during firing is DANGEROUS & they should help you right away . Quote Link to comment Share on other sites More sharing options...
gnatshooter Posted May 23, 2014 Report Share Posted May 23, 2014 My local gunsmith here says that DPMS always over-torques their barrels, barrel nuts, barrel extensions and handguards. Obviously this loose barrel is an exception. Hope this info helps. Quote Link to comment Share on other sites More sharing options...
edgecrusher Posted May 23, 2014 Report Share Posted May 23, 2014 1. If I don't release the charging handle cleanly, the bolt doesn't go into full battery. Since there is no forward assist, I would try pulling the charging handle back a little and re-releasing... sometimes it would work & sometimes it would push another round in under the one already chambered. Possibly a break-in issue that would clear up after some use, possibly a training issue that would clear up after some practice. Regardless, I've decided that this is fine for a bench rest rifle, but it isn't an issue I want present on a tactical rifle. Solution: change uppers to one with the built in FA and ejection port cover. This is not necessary, let that thing slam home, you're not helping anything by doing that. Welcome to the forum, good luck, but don't try to fix that barrel, it's nothing but a bat now. DPMS should take care of that, it's pretty unusual. Quote Link to comment Share on other sites More sharing options...
Alamo Posted May 24, 2014 Author Report Share Posted May 24, 2014 Hi survivalshop, when I 1st took it apart, I only unscrewed the gas block and pulled the tube out of the receiver. Didn't disconnect the tube from the block and didn't remove the muzzle brake, just slid the block up the barrel so I could see what was going on. When I took it to the gunsmith, he disconnected the muzzle brake (it was on so tight he almost had to cut it off) and removed the block to work on it. Still all OEM parts on a factory built rifle. Quote Link to comment Share on other sites More sharing options...
Alamo Posted May 24, 2014 Author Report Share Posted May 24, 2014 Thanks edgecrusher, looks like I just need to learn how to use the charging handle properly as opposed to getting FA. Got a question for you. Since the barrel / nut setup is not typical, wouldn't keeping the barrel mean I couldn't install most aftermarket free float tubes (like a Troy TRX) since they use a proprietary barrel nut which works with the standard (non threaded) barrel attachment method? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted May 24, 2014 Report Share Posted May 24, 2014 Barrel extensions are torqued to barrels at 175lb/ft. That's a hell of alot of torque. That's all during the manufacturing process of the barrel itself, and not a "user maintenance" area. Nothing you've done to the rifle should have made that extension loose, so you're good to go. First, the extension goes on the barrel, the extension is trimmed if necessary to meet proper headspace. Then the barrel index pin goes in 180 degrees off the bottom of the extension. Then gas port gets drilled. You can't just retorque the extension and call it good, That's why the guys are saying your barrel should be replaced - that's the proper thing for the manufacturer to do. <thumbsup> Quote Link to comment Share on other sites More sharing options...
shibiwan Posted May 24, 2014 Report Share Posted May 24, 2014 (edited) Isn't the index pin supposed to go through the extension and lock the extension into the barrel too? Alamo, send it back. The entire barrel is off now and at the bare minimum it needs a new headspace check when it is reassembled back on the barrel extension. Edited May 24, 2014 by shibiwan Quote Link to comment Share on other sites More sharing options...
98Z5V Posted May 24, 2014 Report Share Posted May 24, 2014 Isn't the index pin supposed to go through the extension and lock the extension into the barrel too? Nope, common misbelief. The index pin does not lock the extension to the barrel. It never should. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted May 24, 2014 Report Share Posted May 24, 2014 Barrel extensions are torqued to barrels at 175lb/ft. That's a hell of alot of torque. That's all during the manufacturing process of the barrel itself, and not a "user maintenance" area. Nothing you've done to the rifle should have made that extension loose, so you're good to go. If the Muzzle device was Loctited on , it may take more than the 175# to get it off & if as I said , barrel not in a vice block , you could damage or tweak or break, the upper receiver also . Now if heat was used to soften the Loctite , it should come of with out much trouble . Might also be defective threading on Barrel/extension , that let it loosen up , hard to tell on a PC . <dontknow> It happens more than people will admit & since he also said , his Smith had a hard time getting the Muzzle device off , makes one wonder , how it was removed . Still , talk to DPMS , they will not try to repair that barrel/extension , they will replace it . Loosening during firing , sounds like a thread problem & I would not shoot it again until issue is resolved . Quote Link to comment Share on other sites More sharing options...
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