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Posted: 10/4/2014 4:15:19 PM EDT
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Hi, I just built a 9mm SBR on a DDLES lower for glock magazines. It has a RRA upper, RRA bcg with the mod needed for the lower. A Tros 5" barrel, RRA lpk with the hammer replaced with a Brownells 9mm hammer, a BCM charging handle. And a Spikes BAR hand guard.
When I install the upper onto the lower it fits very tight, it seems like there is extra resistance when I pull the charging handle and the bcg goes back and locks into place. I push the bolt release and the bolt flies forward ok. It dry fires ok. Then when I try to pull the charging handle back again it is stuck. I take the upper off and put it back on and it usually loosens up again for one more cycle. If this makes sense at all, does anyone have any ideas as to what's cauaing this?? I did some research and I felt like I paired everything together so it's all compatible but I may have been wrong? Please help! |
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This may sound odd, but look at the inside of the upper receiver where the charging handle rides. Look for any extra material on the "ceiling" of that channel near the rear of the receiver. I had one that wasn't machined right and it would bind badly in that spot.
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You don't need to worry about the 9mm specific issue with the lower - just put it on another lower and see if the bolt moves freely with that other lower. In particular, you want to see how it feels when you "charge" the upper by pulling back on the charging handle. If it feels substantially different from the way it does with your 9mm lower, that may be important. If it doesn't feel any different, then it's time to examine the innards of that upper.
Start with the charging handle tunnel - compare the 9mm upper's tunnel to a 5.56mm upper's and look for variations, extra material, etc. Swap charging handles and try the 9mm gun with all your 9mm parts except use the other charging handle. Put your 9mm bolt in your 5.56 and see if it moves freely with either charging handle. The Colt-style 9mm AR was built with standard M16 parts. ALL Colt-style 9mms should work with any in-spec upper, lower, charging handle, etc. What's going on right now is a problem playing hide and seek with you, so you may have to poke around plenty to find it. |
| I have run into an issue with a RRA bolt that was modded for a Glock lower that needed to have the ramped area widened.....be glad to slip it into one of my guns and check it if you can't solve the problem.....it'll be hard to see but paint it with dykem and let it dry.....then cycle it and look for where it is rubbing.....you could also paint it white on the bottom.... |
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