survivalshop Posted February 2, 2011 Report Share Posted February 2, 2011 I answered a thread on another forum , because of a problem with a CMMG bolt catch . I also have had the same problem as the poster & finally got time to play with repairing it .The problem is not holding the bolt back on last round consistently or not at all ,even though the rifle functions properly as far as feeding & ejecting .Using both a 308 or a std M15/16 Bolt catch doesn't make a difference, still no hold back.Also the catch when manually operated will not hold it for a second ,if that .With a empty mag in the rifle ,it is not much better.I started by comparing the lift that each mag (different manufacturers ) produced on the catch with an unaltered DPMS lower that's on my 20" rifle ,because it has worked flawlessly.I than, of course, measured the CMMG lower to compare . Measurements were taken with a DPMS 308 Bolt Catches. I than took material off the stop area of the Bolt catch ( where the spring buffer comes in contact )to match the height of the DPMS lowers Bolt Catch.DPMS (unaltered)--CMMG (before)--CMMG(alt)PMAG--0.449" -----0.424" --------- 0.4665"Cprod.-0.399" ----- 0.378" ---------- 0.4015"DPMS--0.456" ----- 0.431" ---------- 0.4750It looks like there is not much difference ,but it made a big difference in function. The catch even holds after mag has been released & works manually & holds .I will take the CMMG to the range tomarrow to test some new loads with the Chrono . The 308 BC & AR 15/16 catch. Material already removedA AR15/16 catch & 308 catch side by side .And the Bolt catch blued with Brownells 44/40. Quote Link to comment Share on other sites More sharing options...
Matt.Cross Posted February 2, 2011 Report Share Posted February 2, 2011 Nice job! Do-it-yourselfers rock! ;D Quote Link to comment Share on other sites More sharing options...
survivalshop Posted February 2, 2011 Author Report Share Posted February 2, 2011 Thanks . It seems some CMMG 308 lowers are not to proper spec's . If they were, I or we would not have to do any kind of special fitting.I do not think I will ever buy any Major part from a manufacturer that makes uppers or lowers & doesn't make complete rifles as was the case of early CMMG 308 lowers.Hay , Doc , are you reading this . Quote Link to comment Share on other sites More sharing options...
TacBlade Posted February 2, 2011 Report Share Posted February 2, 2011 Good Stuff!!!! Quote Link to comment Share on other sites More sharing options...
survivalshop Posted February 17, 2011 Author Report Share Posted February 17, 2011 Testing was done today with three different manufacturers mags. All mags worked, with the bolt catch working on all three different manufacturers .Two Pmags, two Cproducts & two DPMS mags. I used these mags because ,they all would not work the bolt catch after last round.I will be testing new mags of each manufacturer in the coming weeks .I will be unwrapping them & testing .If I could only get Pmags to fire a complete 20 rds with out a FF , I'd be Happy with this CMMG lower , but hay ,I got the Bolt catch to work. Its a start . Rifle has no problems with DPMS or Cproducts mags.. WTF Quote Link to comment Share on other sites More sharing options...
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