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Posted: 5/15/2013 12:09:29 AM EDT
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I've built a couple AR's and I've had my share of problems. From Gas port misalignment to you name it. I have a new problem that I haven't been able to google to figure out so - I've come to the pro's.
This project was to upgrade a S&W stock AR15 with the following. - Magpul B.A.D (Battery Assist) - New grip - Floating barrel guard The AR shot fine prior to the mods and after the mods, it shot fine for about 50 rounds and then the following problem. - Shoots 1 round - Ejects spent cartridge - Does not load next round. - Does cycle through to where I can pull the trigger with empty chamber. The only thing I can think of is the barrel not being torqued appropriately. My AR wrench didn't fit the floating barrel. I ordered another and it should be here tomorrow. The barrel has not come loose that I can tell. Could the barrel tightening be the problem? Thanks in advance! |
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It could be short stroking.
Possible causes: 1. weak ammo 2. to heavy of buffer or buffer spring 3. mis-alignment of gas block after reinstall during free float install 4. gas tube real dirty 5. barrel gas port too small 6. BCG is to heavy When it does eject, where does the brass land? 
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Quoted: You are losing gas somewhere, since you have dicked with the barrel, Im putting money on the gas block alighment.- Shoots 1 round - Ejects spent cartridge - Does not load next round. - Does cycle through to where I can pull the trigger with empty chamber. what type of gas block, what type of ff tube, did it have a handguard on it before-did you allow space for it??? I would also remove the bad until it starts working. |
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Sorry it to so long to get back to this thread and thanks all for the information.
I got it down to three possible problems. The barrel wasn't tight enough (the top rail was off a hair and I was able to line the upper receiver rail with the hand guard top rail by hand), gas block was off a bit (I doubt this because I've had the problem before and have that down) or the Magpul B.A.D. lever was the problem (you can see in resting position it touching the side just a hair which opens the lever up just that much). I cleaned her up, bought and used a torque wrench this time and went back to the range. I put another 30 rounds through it and there wasn't any problem at all. If I had the time I would have trouble shot better but life kicked in and, well, you all know how that goes. The only thing I have left to do is keep on shooting because the problem didn't happen last time till after about 40 rounds. Sloppy trouble shooting, sorry! |
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So rifle had a conventional hand guard on it before I take it -- if so, did you allow for the spacing for the discarded hand guard cap when you re-aligned the gas block?
It's enough to restrict gas port a bit if you snugged it up to the barrel recesses without adjusting for the slight width of the missing cap, and a little bit goes a long way on port size and alignment. Something I hadn't thought of before reading about a similar prob after reconfiguring one that ran fine before free float was added and gas block changed. Really does sound like simple undergassing to moi, looking at what few things you did. - OS |
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Don't believe the BAD lever is causing the feeding issues, it is usually responsible for the bolt not locking back when empty.
I would bet gas block alignment is causing your problems. When you pull your gas block off look for the larger burnt circle around the gas port. See if the gas port on the barrel was inside the hole in the gas block. If not re-align the gas block and test fire to see if it works again. |
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