lablover Posted June 12, 2015 Report Share Posted June 12, 2015 (edited) I have a DPMS buffer spring and buffer for my Mega Arms Mahten build. Been having issues with the BCG not locking back on last round with gas block opened wide open. I also thought I had a pretty rough chamber so gave Mega Arms a call and they said send them the upper. Just got done talking to them and they replaced the barrel for me, did all the work etc and test fired on the Lower they have..All is well. After some conversation they said they think I'm using the wrong Buffer Spring Like I mentioned I'm using the 38 coil DPMS spring. The lower they have is using a 34 coil spring and thats what they think the issue was. I guess after all that I did some research and it seems the AR-10 buff spring is 34 coils and the DPMS is 38 coils. Should I be using the 34 coil spring? My spring is 38 coils 12 1/2" long relaxed Buffer is 5 1/4 long. They are also sending me a 34 coil spring and said give it a try. Could using the lighter spring cause any damage? I also have a Adj gas block. This would be hilarious if this was the root of all my problems. Good news is Mega caught the rough chamber and replaced it free of charge and did all the work on the upper. Kudos to Mega Arms BTW, all full length rifle stock and tube MAgpul PRS stock Edited June 12, 2015 by lablover Quote Link to comment Share on other sites More sharing options...
98Z5V Posted June 13, 2015 Report Share Posted June 13, 2015 Just because it's less coils doesn't mean it's a lighter spring. Wire diameter is the greatest factor in spring strength. Quote Link to comment Share on other sites More sharing options...
wetncold Posted June 13, 2015 Report Share Posted June 13, 2015 Get a Tubbs spring. Takes 3 men and a small boy to get it in but it works great. Quote Link to comment Share on other sites More sharing options...
lablover Posted June 13, 2015 Author Report Share Posted June 13, 2015 I'll look into those. I need to know what the big difference is between the 34 and 38 coil...I'll check spring wire thickness when I get the one from Mega Quote Link to comment Share on other sites More sharing options...
lablover Posted June 20, 2015 Author Report Share Posted June 20, 2015 (edited) Well Got the upper back from mega and the new buffer spring they sent along.....98Z was on the right track I think. The new spring Diameter was .072 as opposed to the DPMS 308 spring I had that was...get ready for this...082 wire diameter. No wonder my freakin bolt would not lock back. At first I thought the 308 spring Mega sent me was too lite so I found this diagram and noticed .072 dia is right on track. WTF is DPMS thinking putting such a heavy spring in that stock kit they sell. After doing some snooping here I found a few other people having the same issue and all had that Damn DPMS .082 dia spring. and it has 38 coils. I have not test fired yet but I'm almost positive that was the issue. Now, to make another upper in 6.5 creedmoor....hmmmm where to get a barrel??? Edited June 20, 2015 by lablover Quote Link to comment Share on other sites More sharing options...
98Z5V Posted June 20, 2015 Report Share Posted June 20, 2015 WTF is DPMS thinking putting such a heavy spring in that stock kit they sell. They put their own version of an AR15 spring in it. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted June 20, 2015 Report Share Posted June 20, 2015 There is nothing wrong with the DPMS components when used with the proper Receiver Extension on a DPMS 308 rifle & most of the other DPMS compatible Receiver sets . The facts are that there is no standard with some manufacturers Receiver sets . If you had a DPMS set up , the components you have would work flawlessly . Just ask the tens of thousands of LR 308 AR owners out there, that have great running rifles with their DPMS components . Blaming DPMS for their components not working in your after market copy or version of their design , is absurd . <dontknow> Quote Link to comment Share on other sites More sharing options...
lablover Posted June 20, 2015 Author Report Share Posted June 20, 2015 There is nothing wrong with the DPMS components when used with the proper Receiver Extension on a DPMS 308 rifle & most of the other DPMS compatible Receiver sets . The facts are that there is no standard with some manufacturers Receiver sets . If you had a DPMS set up , the components you have would work flawlessly . Just ask the tens of thousands of LR 308 AR owners out there, that have great running rifles with their DPMS components . Blaming DPMS for their components not working in your after market copy or version of their design , is absurd . <dontknow> Hmmm I used a DPMS Receiver Extension, DPMS Stock...Heck, I bought the whole thing as a DPMS Kit. So, just not having DPMS receiver set was the issue...Wow...tons to lean for sure! I wasn't really blaming them and if I did...opppsss Quote Link to comment Share on other sites More sharing options...
survivalshop Posted June 20, 2015 Report Share Posted June 20, 2015 Since all these other manufacturers jumped on the 308AR band wagon , with there own version of a compatible DPMS Receivers sets ,there have been minor & some major fitment problems on some of them . Not your fault that you didn't know or wasn't aware of a fitment problem with this manufacturer or it needing a particular set of components . <thumbsup> Its Tolerance stacking , we have been working on these issues with other members here & its also a learning process for us too . If you read enough of the problems that are faced with some of these builds , it boggles the mind how a manufacturer can produce a product which I for one wonder about their Quality control or R&D testing . I personally would not purchase a Receiver set from a manufacturer that didn't make complete rifles . Sure a lot of builds are made with some that are not , but I can't see how a Manufacturer can produce something that is not been tested with a complete functioning rifle . Maybe most do , but some seem to be have fitment & function problems that one would think would show up in testing . <dontknow> Once it gets to manufacturing , it could go out of spec's also. I have three 308ARs , one ( my first build ) has DPMS factory Receiver set , two, has a DPMS Factory Complete Lower with a Tactical Machining Upper Receiver & the third ( Which is waiting for me to buy a new Barrel for it ) has a very early CMMG Billet Lower & a Gen II ,SI Defense Billet upper . This last combo will function flawlessly with any Metal mag put in it , but put a PMag in & it will fail to feed reliably . That there is Tolerance Stacking , can't blame CMMG or SI defense , because the PMag for LR 308AR's was just a dream for us & Magpul back then . Its like putting Quarter in the Receiver Extension for the Buffer system to work correctly , sorry 98 , I couldn't resist the fitment problem <lmao> Quote Link to comment Share on other sites More sharing options...
lablover Posted June 20, 2015 Author Report Share Posted June 20, 2015 Well said! These big boys are a whole new process for me for sure.. Thanks Quote Link to comment Share on other sites More sharing options...
98Z5V Posted June 21, 2015 Report Share Posted June 21, 2015 Its like putting Quarter in the Receiver Extension for the Buffer system to work correctly , sorry 98 , I couldn't resist the fitment problem <lmao> Just goes to show, it happens. Doesn't matter who makes it, we know what breaks it, at this point in the game. It's more than one quarter, too... <laughs> The last one I built (just got the parts in), I went Armalite AR10 Carbine receiver extension with the AR15 H3 buffer, and the Armalite 1095 spring. We'll see how that one runs when I get it together. Quote Link to comment Share on other sites More sharing options...
lablover Posted June 24, 2015 Author Report Share Posted June 24, 2015 Got her to the range with the new spring...Shot without an issue...Woooohoooooooo Now to find an accurate e load it likes Quote Link to comment Share on other sites More sharing options...
taffrail Posted June 25, 2015 Report Share Posted June 25, 2015 Think they put the wrong spring in your kit. DPMS calls for 11.5" spring. My wire diameter measures .072" which is a tad small or the measuring device made a booboo. Sounds like the spring you have now is the one that should have come in the kit. Send it (the spring not the kit) back to whomever you bought it from. Explain in gentle kind terms how much their brief hiccup in an otherwise stellar performance cost you some money and a good bit of consternation. If that don't work, tell em you are sending 98............... Quote Link to comment Share on other sites More sharing options...
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