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Posted: 6/12/2013 7:21:04 PM EDT
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Hey guys, new to the forum here. I have been reading it for a while, but finally registered today.
First off, I have searched the forums and can not find a problem like this, maybe I have not dug down deep enough into the forums over the last few weeks. I have a clone/no name brand 7.62x39 AR upper and the bolt will get stuck after a round is fired off. I have to eject the mag, then pull back on the charging handle and use a screw driver to pry the bolt back to eject the shell. I have used this on 2 different 5.56/multi cal lowers. After a very good cleaning I can get 4 to 5 rounds to cycle really well, then the problems start where the shells wont eject. I checked a few spent rounds and did not notice any unusual markings on the casing. The charging handle and bolt do move freely with out any resistance just like my 5.56 AR's. I am using cheap steel case Tula ammo, and have recently ordered 100 brass rounds to give that a try to see if it still happens with the brass. I have made sure the gas block is not clogged and aligned properly, and the gas key is secure. I have tried 2 different makes of magazines, fully loaded and partially loaded. I have yet to try a single round with out the mag. Im not sure what else to check, any suggestions will be greatly appreciated. James |
| Your decision to try different ammo is the best one to try first. Sometimes the chamber can be a little rough and as residue from firing builds up the cases begin to stick. Steel cased ammo is known for that. I have taken a rifle rod and wrapped a bore brush with 0000 steel wool, chucked it in a drill and stuck the steel wool in the chamber and ran the drill at a low speed to polish the chamber a little. The idea is to polish without removing any metal. |
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maybe this 7.62 upper is very picky. I have gone through just over 2 thousand rounds of that cheap Tula steel case ammo in my Stag Arms 5.56 and have not cleaned it and its going strong with out any problems other than a FTF a few times and maybe 3 FTE's that were easily taken care of.
I have some soft polishing cones coming for my dremel, I will give that a shot as well. |
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Quoted:
maybe this 7.62 upper is very picky. I have gone through just over 2 thousand rounds of that cheap Tula steel case ammo in my Stag Arms 5.56 and have not cleaned it and its going strong with out any problems other than a FTF a few times and maybe 3 FTE's that were easily taken care of. I have some soft polishing cones coming for my dremel, I will give that a shot as well. What are you planning on polishing? |
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update:
I polished the feed ramps pretty good, but not so much to cause any trouble, I also very slightly polished inside the chamber. I cleaned up everything very nicely and oiled it up pretty good. I received 100 rounds of BRASS 7.62x39 FMJ. I get out to the range today and I went through 60 rounds of the BRASS with out any failures. the casings were ejecting much better and further than before and better than the steel case stuff. I then started shooting the steel case FMJ's and I got about 250 rounds through it then the trouble started again. however none of the casings got stuck where i had to forcefully pry the bolt back to eject the casing. I also had a lot more FTF, but I guess thats more of a magazine issue. I get home and tear it down to clean it and there is no real build up of gunk from the cheap ammo, but maybe its enough for this picky upper. One thing that I can think of that was the source of the initial failures was the Tula (and other brands) of the 124gr SP (soft point) that has the lead tip. I recalled when I was having these problems the first few times, when i switched to the FMJ's of the steel case, I had less troubles. Maybe my 7.62x39 upper does not like the 124 Gr Sp. So those have been set aside to make sure i wont use them again. Im going to stock up on some more brass and see if I can get 300 to 500 rounds down range with out any problems to completely rule out the Tula ammo and that its not some other problem. James |
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