R0CKNR0LLKL0WN Posted January 17, 2015 Report Share Posted January 17, 2015 Hey Gents, New to this forum. I just recently finished my first build and I'm having an issue with the bolt not locking back after the last round is fired. Looking for some advise. Components list is as follows: Mega Maten Upper/Lower Billet set JP Supermatch 20" barrel, rifle length gas system JP adjustable gas block JP silent capture spring in A2 Reciever extension JP LMOS Bolt carrier CMMG MK3 Lower Parts Kit Magpul SR25 Pmags The rifle cycles fine other than a couple double feeds when under gassed. The bolt locks back just fine manually with an empty mag installed. Tried adjusting the gas block all the way open. Still not locking. Tried using Mil Surp 7.62, ZQ1 7.62, and .308 hand loads. Also tried 3 different mags. I noticed that the spring tension on my bolt catch is a little more than any of my other rifles. Could that be the issue? Any input would be greatly appreciated. Quote Link to comment Share on other sites More sharing options...
unforgiven Posted January 17, 2015 Report Share Posted January 17, 2015 Welcome from Indiana brother,someone will come along to help you. Quote Link to comment Share on other sites More sharing options...
R0CKNR0LLKL0WN Posted January 17, 2015 Author Report Share Posted January 17, 2015 Here's a picture of her. Looking good. Just not running so good. Quote Link to comment Share on other sites More sharing options...
unforgiven Posted January 17, 2015 Report Share Posted January 17, 2015 I like the look.Some have had problems with CMMG parts. <dontknow> Quote Link to comment Share on other sites More sharing options...
wetncold Posted January 18, 2015 Report Share Posted January 18, 2015 Check your mags. They are what locks the bolt back. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted January 18, 2015 Report Share Posted January 18, 2015 (edited) Have you tried function with Standard 308 rifle spring & Buffer ? Edited January 18, 2015 by survivalshop Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted January 18, 2015 Report Share Posted January 18, 2015 I like the look.Some have had problems with CMMG parts. <dontknow> That's an understatement... First, take out your bolt catch assembly (catch, detent and spring). Replace it with a simple Armalite or a Phase5 EBRv2. Second, pull the entire trigger group out. Replace it with a Geissele, ALG or a CMC. Third, pull the fire control and replace it with a BAD Inc, AXTS or similar ambi set-up. .... do you see where I'm going with this??? Take down and pivot pins are next. Don't forget their respective detents and springs. DPMS parts will suffice here. The magazine catch should be next. The Armalite AR10A will fit. It's beefier than the LR308 version (which is just an AR15 part). Might as well get a Norgon or Troy left side release while you're at it. I'm pretty sure I've "cleansed" your rifle at this point. Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted January 18, 2015 Report Share Posted January 18, 2015 I just really hate seeing all those high quality Mega and JP parts get uglied up with cheap CMMG crap. Kinda like seeing a guy who owns a Ferrari, shopping for tires at Walmart. Quote Link to comment Share on other sites More sharing options...
R0CKNR0LLKL0WN Posted January 18, 2015 Author Report Share Posted January 18, 2015 (edited) Thanks for all the input guys. I had a feeling that CMMG parts weren't the best way to go. I'm going to replace my bolt catch and spring with an Armalite. We'll see how that goes. As far as the trigger, it's a Geissele SD-E. Edited January 18, 2015 by R0CKNR0LLKL0WN Quote Link to comment Share on other sites More sharing options...
R0CKNR0LLKL0WN Posted January 18, 2015 Author Report Share Posted January 18, 2015 And no, I haven't tried a standard buffe and spring yet. That'll be next. Quote Link to comment Share on other sites More sharing options...
shibiwan Posted January 18, 2015 Report Share Posted January 18, 2015 I just really hate seeing all those high quality Mega and JP parts get uglied up with cheap CMMG crap. Kinda like seeing a guy who owns a Ferrari, shopping for tires at Walmart. Call it what you want but mine runs and shoots great. So :fawkdance: Quote Link to comment Share on other sites More sharing options...
mineralman55 Posted January 18, 2015 Report Share Posted January 18, 2015 How many rounds have your put down the pipe? Mine needed ~120 before it reliably locked back when empty. It just needed breaking in. that's all. Since then, not a single problem. Quote Link to comment Share on other sites More sharing options...
FaRKle! Posted January 18, 2015 Report Share Posted January 18, 2015 Does the gas tube protrude far enough into the upper receiver? Lately I've been seeing more and more posts about undergassed builds where they needed an AR-10 pattern gas tube instead of AR-15/LR308. JP is known as a quality manufacturer, but it'd be easy to check anyways. Quote Link to comment Share on other sites More sharing options...
R0CKNR0LLKL0WN Posted January 18, 2015 Author Report Share Posted January 18, 2015 How many rounds have your put down the pipe? Mine needed ~120 before it reliably locked back when empty. It just needed breaking in. that's all. Since then, not a single problem. Well, took it to the range again today without doing anything to it. Fired about 100 rounds without a single issue... I think mineralman55 was right, just needed a little breaking in. Quote Link to comment Share on other sites More sharing options...
mineralman55 Posted January 20, 2015 Report Share Posted January 20, 2015 Well, took it to the range again today without doing anything to it. Fired about 100 rounds without a single issue... I think mineralman55 was right, just needed a little breaking in. I never lie, and I'm always right. :)) Quote Link to comment Share on other sites More sharing options...
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