atxhoghunter Posted May 15, 2014 Report Share Posted May 15, 2014 Yesterday was my first test-fire of a DPMS LR-308 build. Upper came complete from DPMS/MidwayUSA. Lower is an 80% I finished myself. Rifle is extremely accurate. Fired 40 rounds. Followed break-in/cleaning procedures. Last three rounds were sub MOA at 100 yards. Love it. Issue #1: If I put more than three rounds in any of my magazines (DPMS metal 20 round, Magpul 10 round, Magpul 20 round), the bolt has trouble stripping the round when you attempt to manually cycle with the handle, The result is the bolt only closes about 95% of the way. The bolt is then extremely difficult to pull open/eject the poorly seated round. Makes no diffence if you insert the magazine when the bolt is open or closed. The barrel is carbine length with a DPMS .308 carbine buffer spring and carbine buffer. More perplexing is that when testing with .308 SnapCaps, of which I have ten, there are no failures to strip/feed. Keep in mind this is all happening prior to firing the gun. No gas issues. This issues is specifically stripping the round from the magazine and seating it properly when the magazine is under pressure with 4 or more rounds. Issue #2: After returning from the range I mocked-up 20 rounds of ammo (no powder or primer) with Sierra Gamekings with a COL of 2.7" (midway between the 2.8" Hornady Match ammo I test fired, and the 2.55" SnapCaps). Used Gamekings because their shiny/single-metal surface would show if/where the bullets might be hitting the ramp or rifling. A noticeable mark is being left on each bullet when the rifle is being cycled manually. Starts near the tip of the bullet and twists down half the length of the ogive, decreasing in depth as it goes, then disappears. Seems to me that means its catching on the rifling somewhere. The brass is undamaged. I did notice that the 10 SnapCaps also have some nicks on their bullet sections, but have fed flawlessly. Here are my possible fixes. Please add or redirect when you see something that won't work. Clean and Lubricate: Sure seems like I did all that, but maybe with its first firing some hidden fabrication grit broke loose. Polish M4 Feed Ramps: I know some folks say this doesnt help, but it might work. Extra Power carbine buffer spring: Have one on order from Sprinco. Will be good to have as a spare, even it that's not the fix. Purchase and use a .308 small base die set. Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted May 15, 2014 Report Share Posted May 15, 2014 Lube lube lube looooooooob. Chuck a chamber brush into a rotary tool, lube it up, then run it a few seconds in the breach. That'll soften things up a bit. Leave your mags fully loaded for a few nights. That should decompress them a bit. Also check the lips for any snags that might be dragging on the brass. A heavy buffer will help you too. Check out heavybuffers.com (most of us have gone this route) Quote Link to comment Share on other sites More sharing options...
washguy Posted May 15, 2014 Report Share Posted May 15, 2014 What Robo said ! One a new build you can hardly ever cycle by hand....but get some lead down the pipe to lossen things up...gas rings/cam /bolt wearing in.and the mags....if it cycles on live fire....and locks back on one round you are good to go :) Wash Quote Link to comment Share on other sites More sharing options...
survivalshop Posted May 15, 2014 Report Share Posted May 15, 2014 (edited) The marks on the bullets are probably locking lug marks from the barrel extension . Was the barrel /bolt head spaced ? Did you do the drill , one round fired to see if the BCG is held back with empty mag. ? Since the fresh round is almost going into battery , could be a head spacing issue, burr on locking lugs , chamber issue ( its a DPMS factory upper ) , like Robocop said , clean the crap out of the chamber & barrel extension area. Do not be afraid to oil the crap out of her , run her wet , keep lubricant out of the chamber. Those snap caps are not to spec's , so don't expect them to act like a loaded round . The feeding problem may be that she is just tight & needs some break in time & lubricants. Now one other thing , are you sure the lower was machined to spec's , & I mean sure ? Edited May 15, 2014 by survivalshop Quote Link to comment Share on other sites More sharing options...
atxhoghunter Posted May 15, 2014 Author Report Share Posted May 15, 2014 Thank you for the good responses. Hopefully it is a lube and break-in issue. Will tinker with it as time allows. As for the lower being in-spec ... according to my micrometer it is. I butchered a .223 lower a few months ago as a warm-up. Learned from that. Interesting no one espouses the small based dies. Quote Link to comment Share on other sites More sharing options...
Tripledeuce Posted May 15, 2014 Report Share Posted May 15, 2014 Are you "following" the charging handle down? or letting the bolt slam home from the locked position? Respectfully Terry Quote Link to comment Share on other sites More sharing options...
planeflyer21 Posted May 15, 2014 Report Share Posted May 15, 2014 Are you "following" the charging handle down? or letting the bolt slam home from the locked position? Respectfully Terry Great question right there. Get that all the time with students. Quote Link to comment Share on other sites More sharing options...
atxhoghunter Posted May 16, 2014 Author Report Share Posted May 16, 2014 Learned years ago during my SKS stage to let the bolt slam home. Definitely doing it now that I'm in my AR phase. In an attempt to summarize more clearly ... the rifle functions flawlessly (in every way) as long as I don't have more than 3 rounds in the magazine. It locks open on the last round, shoots sub MOA, strips, feeds, fires and ejects. Will clean and lube tonight and hope for a kitchen-pass to the range early one morning this weekend. Quote Link to comment Share on other sites More sharing options...
edgecrusher Posted May 16, 2014 Report Share Posted May 16, 2014 Well I'm not sure this is your issue but try running it ridiculously wet. Also, in addition to the others suggestions, what bolt catch are you using, and lower parts kit? Quote Link to comment Share on other sites More sharing options...
Magwa Posted May 16, 2014 Report Share Posted May 16, 2014 (edited) One question what kind of ammo? whatever it is try something else no handloads buy some factory good stuff and see if this problem repeats....... a pic of the bolt after being fired it needs to be dripping wet.... with LOOOOOOOOOOOOOOOOOOOOOOOOB .. :) Edited May 16, 2014 by Magwa Quote Link to comment Share on other sites More sharing options...
washguy Posted May 16, 2014 Report Share Posted May 16, 2014 ATX use factory loads at first if you arnt....3 with no probs and then probs no matter what mag....something is causing that mag prob.....hopefully just a new piece....hope its not your machining :) Wash Quote Link to comment Share on other sites More sharing options...
survivalshop Posted May 16, 2014 Report Share Posted May 16, 2014 (edited) If you want info on Small base dies , see the reloading section , but I use them still & Full length also . I have a thread in the reloading section on them . You could also have issues with your reloads, you say the BCG is difficult to pull back with a live round in the chamber , that could be a sized case problem , not sized properly or trimmed , they can get a little sticky with tight chambers. You also said you have a 308 carbine spring & buffer , could you measure the spring & buffer & also weigh the buffer & we like photo's here. Edited May 16, 2014 by survivalshop Quote Link to comment Share on other sites More sharing options...
atxhoghunter Posted May 16, 2014 Author Report Share Posted May 16, 2014 No reloads fired to date. Forty rounds of factory Hornady Match ammo is all that's gone down the pipe. Will weigh the buffer tonight. Quote Link to comment Share on other sites More sharing options...
gnatshooter Posted May 16, 2014 Report Share Posted May 16, 2014 Something similar to this happened with my Marlin 9mm 'Camp' rifle. I bought an extended (25-round) magazine for it. If I loaded more than 5 rounds into the magazine, it would not feed. The problem was that the cartridges were ever so slightly too long for the internal dimensions of the magazine, and would jam. Or, stated the other way around, the internal dimensions of the magazine were ever so slightly too small. But, and this is an important caveat, I was unable to load more than 5 rounds. These were factory ammo and an aftermarket magazine. No problems at all with factory ammo and the factory mags. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted May 16, 2014 Report Share Posted May 16, 2014 (edited) I would say also , it seems like you have more than one issue to be cleared up , focus on one at a time ,although its posable they could all be related. . You should not have any problems striping a fresh round from the mag. if all is proper with components , could be binding some where along the line . Your hammer could be slowing the BCG down , what could happen with the hammer is , it comes in contact with the Disconnect & the BCG instead of just the spring pressure to overcome , its binding between the hammer & disconnect ,enough to slow the action down enough to cause malfunctions. That is one direction you can go , just anther thing to think about . There will be a mark on top of the disconnect . If the FTF is with all different manufactured Magazines , its more than likely its not the Magazines. How tight is you magazine catch ? Do your mags drop free when released ? No reloads fired , OK , what was the purpose of the Mocked up Game kings , did they feed & chamber properly ? Edited May 16, 2014 by survivalshop Quote Link to comment Share on other sites More sharing options...
atxhoghunter Posted May 17, 2014 Author Report Share Posted May 17, 2014 A thorough cleaning, a new brand of lubricant, and the discovery/sanding of a rough spot inside the upper receiver and my .308 now will strip and fire from a fully loaded magazine. Found a very limited amount of "dirt" duirng the cleaning. Not more than you'd expect from firing 40 factory rounds. Changed from the lubricant that's seen me through a half dozen mauser builds (Rem Oil in the spray pump) to the incredibly slick FP-10 from Shooter's Choice. That seemed to make the biggest difference. Did find a mysterious rough area inside the upper receiver (where the bolt travels) that knocked-down with some brushing. Still not completely gone. Can't really see it, but can feel it. Hoping its a foreign body and not an area where the upper was poorly manufactured. Thanks for everyone's help. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted May 17, 2014 Report Share Posted May 17, 2014 (edited) Good job <thumbsup> .Now we need target & rifle photo's or it didn't happen. Edited May 18, 2014 by survivalshop Quote Link to comment Share on other sites More sharing options...
gnatshooter Posted May 17, 2014 Report Share Posted May 17, 2014 Good job <thumbsup> <thumbsup> .Now wee need target & rifle photo's or it didn't happen. My website would be a monster if I did pix of everything. I just shot up some targets this afternoon. If you want to see the the latest results, just go here and scroll down to "Three other kinds of ammo". Turns out, there's a wide range of quality in .22lr ammo. And a wide range of things you can do to improve a Ruger 10/22. If you noodle around, though, you'll find a few pix of blasted targets. Quote Link to comment Share on other sites More sharing options...
atxhoghunter Posted May 22, 2014 Author Report Share Posted May 22, 2014 (edited) DMPS Complete Upper from Midway USA. 80% lower. Simmons Scope. Battle Gray Duracoat. Recoil Eliminator from JP Industries. Ace Skeleton Stock. Hogue handguard with rubberized grip. ERGO rubberized grip (matches nicely/feels great with the Hogue handguard). Edited May 22, 2014 by atxhoghunter Quote Link to comment Share on other sites More sharing options...
gnatshooter Posted May 22, 2014 Report Share Posted May 22, 2014 Pic 1.jpg Pic 3.jpg Pic 4.jpg DMPS Complete Upper from Midway USA. 80% lower. Simmons Scope. Battle Gray Duracoat. Recoil Eliminator from JP Industries. Ace Skeleton Stock. Hogue handguard with rubberized grip. ERGO rubberized grip (matches nicely/feels great with the Hogue handguard). That is one fine looking rifle, the clean, 'utlilitarian' lines are nice. That JP Recoil Eliminator is the final touch that says it 'means business'. I had some correspondence with JP about the Recoil Eliminator a while back. I have their Bennie Cooley oversize muzzle brake, and then there was a website redesign on their end, and they claimed the Recoil Eliminator had less concussion for the shooter than other brakes. Well, I emailed them about that claim and how I already had their Cooley. They said they "doubted" there would be any difference between the two brakes on a .308. Do you have any thoughts on the concussion issue? Quote Link to comment Share on other sites More sharing options...
atxhoghunter Posted May 22, 2014 Author Report Share Posted May 22, 2014 As for the Recoil Eliminator and "concussion" ... It is the most effective muzzle brake I have ever used. Have one on a 7mm STW and it tames it quite nicely. The sound was no more than usual for the shooter. However ... if you are to either side of the shooter ... you will be miserable. Maybe not a concussion, but tinnitus is a big possibility. It is loud. Could have just been the way things worked, but the 9 other stalls at the indoor range were empty by the time I finished by 40 rounds. Quote Link to comment Share on other sites More sharing options...
Toolndie7 Posted May 22, 2014 Report Share Posted May 22, 2014 As for the Recoil Eliminator and "concussion" ... It is the most effective muzzle brake I have ever used. Have one on a 7mm STW and it tames it quite nicely. The sound was no more than usual for the shooter. However ... if you are to either side of the shooter ... you will be miserable. Maybe not a concussion, but tinnitus is a big possibility. It is loud. Could have just been the way things worked, but the 9 other stalls at the indoor range were empty by the time I finished by 40 rounds. LOL I put one of those recoil eliminators on a 300 win mag bolt gun. Its tames it like a champ and the shooter is happy, but yeah off to the side its loud as all hell. The wife will actually shoot it now. Quote Link to comment Share on other sites More sharing options...
gnatshooter Posted May 22, 2014 Report Share Posted May 22, 2014 (edited) Here's where I'm standing on this issue right now. The 'large' JP Bennie Cooley on my LR-308 generates terrific concussion for the shooter You can feel it against your face and it''s really unpleasant. So for that reason I got a 'linear compensator' which does not reduce recoil, but does effectively move the noise away from the shooter and everyone else and sends it downrange. Now, JP said the Cooley and the Eliminator would "probably" have the same concussion for the shooter in a .308. Now I'm hearing I can get recoil elimination and not more concussion -- so I'm severely tempted to get one for my .308. These critters ain't cheap. Edit: I've had the Eliminators on a couple Ruger 10/22s and found they made the rifle more accurate than the 'ported' muzzle brakes I had on the other 10/22s, so an accuracy advantage would be a plus. And the rifle will be used on the farm for hunting and occasional target practice, so I don't care about bystanders most of the time. Edited May 22, 2014 by gnatshooter Quote Link to comment Share on other sites More sharing options...
atxhoghunter Posted May 22, 2014 Author Report Share Posted May 22, 2014 Haven't compared the two JP products, but did not notice any unpleasantness while firing. The .308/.725 Recoil Eliminator that I needed is only available from the manufacturer. Midway/Brownells don't carry it. Quote Link to comment Share on other sites More sharing options...
gnatshooter Posted May 22, 2014 Report Share Posted May 22, 2014 Haven't compared the two JP products, but did not notice any unpleasantness while firing. The .308/.725 Recoil Eliminator that I needed is only available from the manufacturer. Midway/Brownells don't carry it. I've always dealt directly with JP on their items, and they're excellent folks. "Good to go", as they say. 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.