AR15 mags jamming bolt.

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DOA33
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AR15 mags jamming bolt.

Post by DOA33 »

I built a AR15 today. I did a function test at each step and everything seemed to be working correctly. Until I loaded a mag to test fire and it seems hard to click in and once in I can't pull the charge handle at all. I hit the mag release but it stays till I pull it out. I emptied the mag and tried again, same issue. I then pulled the bolt back and locked it, put the mag in, and hit the bolt release. The bolt slammed into the back of the mag and made a cut into the plastic. Is the mag bad or there's something I can adjust? This is my 1st AR I've built myself.
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DOA33
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Re: AR15 mags jamming bolt.

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Update. Tried all my mags, 6 in total. 5 failed but 1 works just fine. All 5 that failed are the pmag gen 2 and the 1 that does just fine is gen 3. Would it be possible to cut the gen 2 to be more like gen 3 or just get new mags?
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TSiWRX
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Re: AR15 mags jamming bolt.

Post by TSiWRX »

^ With your update, I'm suspecting that you're somehow overinserting the Gen M2 PMags (given that the overtravel stop on the Gen M3 seems to have rectified your problem).

Take a look at the magazine catch versus the same on your other -known working- ARs. See if they are engaging in the same manner to start with, before you even pull the parts to see if there's perhaps something wrong with the one that you're having issues with. Swapping the components from one lower to another can also help you pinpoint potential issues.
Allen - Shaker Heights, Ohio
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DOA33
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Re: AR15 mags jamming bolt.

Post by DOA33 »

TSiWRX wrote:^ With your update, I'm suspecting that you're somehow overinserting the Gen M2 PMags (given that the overtravel stop on the Gen M3 seems to have rectified your problem).

Take a look at the magazine catch versus the same on your other -known working- ARs. See if they are engaging in the same manner to start with, before you even pull the parts to see if there's perhaps something wrong with the one that you're having issues with. Swapping the components from one lower to another can also help you pinpoint potential issues.
I have 2 other ARs and both work with all the mags I have. The current AR I'm having trouble with is using a upper I had that worked just fine on a old lower, but than I swapped it to the lower I built.
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Re: AR15 mags jamming bolt.

Post by TSiWRX »

^ So if I'm reading that right, the problem is "following" the new lower, correct?

If so, I would like to see if we can isolate the problem to the magazine catch on the new build. I had similar (but not identical) issue on a self-build, and it was due to incomplete magazine-catch engagement, due to an unforeseen incompatibility between the magazine catch and magazine catch button (neither of which were standard MilSpec parts).

Before tearing anything down to-components, I'd just strip two or three of your ARs (including the problematic one) to complete lowers, and see if there's any differences in how various test magazines are seating within the lowers, paying special attention to any deviations from-normal (i.e. what you see of your two working lowers), with your problem lower. My over-insertion related issue (which is my guess on yours, due to the fact that using the Gen M3 PMag [integral overinsertion-stop] eliminates the problem) became quite apparent when I did this; after which it was pretty easily isolated to the magazine catch components.

Given that a Gen M3 PMag resolves your issues, we can also reasonably assume, IMHO, that your lower is in-spec....but I'm no armorer. :oops: :P
Allen - Shaker Heights, Ohio
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DOA33
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Re: AR15 mags jamming bolt.

Post by DOA33 »

TSiWRX wrote: Given that a Gen M3 PMag resolves your issues, we can also reasonably assume, IMHO, that your lower is in-spec....but I'm no armorer. :oops: :P
I'm happy to hear that it's in-spec considering this is a 3D printed lower. :lol:
I'm just going to buy some gen 3 mags and call it a day. I did run 20 rounds through it yesterday and it ran flawless.
Thanks for the help!
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Re: AR15 mags jamming bolt.

Post by TSiWRX »

DOA33 wrote:
TSiWRX wrote: Given that a Gen M3 PMag resolves your issues, we can also reasonably assume, IMHO, that your lower is in-spec....but I'm no armorer. :oops: :P
I'm happy to hear that it's in-spec considering this is a 3D printed lower. :lol:
Cool!

I've really wanted to get in to 3-D printing, but alas, the pea that I call a brain can't juggle any more hobby. :oops: :P

SOTAR and P&S both have had some excellent videos in the past about magwell dimensional issues....when good mags don't function correctly, that's always one of my bigger worries. With mine, it was more of a "boutique" lower (Battle Arms Development billet lightweight), so when I suffered similar issues, I really was sweating it out for a bit. Luckily, it was my own stupidity -or, rather, just not having looked in-detail enough at the parts that I had in my hand at the time- that was the root-cause.
I'm just going to buy some gen 3 mags and call it a day. I did run 20 rounds through it yesterday and it ran flawless.
Sounds like a plan! Mag prices are pretty good these days, and the Gen M3s are really pretty awesome (well, unless you have a lower that doesn't play well with the overtravel stop, that is! :lol: ), it's a good investment, and if it solves the issue, then all the better. :D
Thanks for the help!
I didn't really help all that much! :oops: Glad you found an acceptable solution. :)
Allen - Shaker Heights, Ohio
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