Ar10 bolt jamming up on PMag/mag release

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this is kind of hard to explain, I am also pretty experienced with the AR platform, my M5e1 upper is assembled on an 80% lower. When I rack the bolt back on an empty magazine my bolt carrier jams up as soon as the carrier reaches the mag release and mag release area of the mag. It jams extremely hard, if I mortar the charging handle I can get the bolt carrier group past the bolt catch and everything then locks back as it should. If I do not mortar the BCG all the way back and drop the mag, the bolt carrier slams forward. I do not understand why the BCG is getting hung up on that spot. I have swapped mag releases and tried a few different PMags, haven’t tried any other mags yet.

Has this occurrence ever happened to anyone else? I can try and provide pictures but it’s pretty difficult to see.
 

2Wheels4Ever

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You could have an out of spec or wrong bolt catch. I'd first try a different magazine, and then switch out to a Aero/different brand bolt catch if the problem persisted. Can you see where exactly the unwanted contact is happening? A white sharpy is a great way to find where the contact it. It might just need a little hand fitting to work perfectly.
 
OP
Mk3Mstr6Mchne0
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You could have an out of spec or wrong bolt catch. I'd first try a different magazine, and then switch out to a Aero/different brand bolt catch if the problem persisted. Can you see where exactly the unwanted contact is happening? A white sharpy is a great way to find where the contact it. It might just need a little hand fitting to work perfectly.
I’ve used an aero ar10 bolt catch and a V7 ar10 bolt catch. I cannot imagine both of those being wrong. They are both reputable reliable companies.
 
OP
Mk3Mstr6Mchne0
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Here you can see the bolt initially caught on the lip of the mag. Upon pulling back harder the bolt becomes hung up on the bolt catch, and the following images show the tooling damage common to the BCG looking from inside the magwell.

I think I’m just gonna buy an M5e1 lower with the hopes the problem is solved.

19D96725-F41E-476C-930E-349FCB49B8CF.jpeg 6299013D-50B1-492F-98B5-1442E3FCD87D.jpeg AD9B3152-10DD-47C7-AD73-B027849C6C5E.jpeg DAFFD712-D2FC-4DB7-992C-DECD231C1B66.jpeg 78946FCE-C6CA-4321-9ED8-FF6ED3A5FB24.jpeg 1A853730-E15B-4F10-85B4-9B7B8118E7B1.jpeg
 

Joe13

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Have you tried swapping BCG's with your buddy's gun?

It would at least rule that out.

Or even try swapping the whole upper to narrow down if it's the upper or lower.


Sounds like an ideal situation if you have access to the exact same rifle owned by a friend.
 
OP
Mk3Mstr6Mchne0
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Is it catching without a magazine in it?. is the spring missing on your bolt catch, or maybe too weak a spring?
Have you tried swapping BCG's with your buddy's gun?

It would at least rule that out.

Or even try swapping the whole upper to narrow down if it's the upper or lower.


Sounds like an ideal situation if you have access to the exact same rifle owned by a friend.
Idk why I have not done this yet. That needs to be done ASAP.
 
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Oil it...This is an AR and AR's like to run wet. That BCG looks very dry as does that entire gun. wetter is better ;)

oil up the mag catch and make sure it moves freely but springs back as it should.

on your mags make sure the followers are springing up as they should and not sticking or jamming up.

make sure the magazine fully locks into place.

Also what brand and generation is your upper receiver, lower receiver, and bolt carrier?

By generation I mean is it DPMS gen1 or DPMS gen2?

From the Magpul website regarding the PMAG LR/SR Gen M3 magazines.
*NOTE: Compatible with older model Bushmaster .308 ORC, Remington R-25, and DPMS LR308 rifles, but not optimized for bolt lock functionality with newer models based on the DPMS GII design. NOT compatible with Armalite AR-10B, Springfield Armory M1A, Rock River Arms LAR8, FN SCAR 17S, PTR-91, HK417 or any other rifles that utilize M14, FN FAL, or HK 91/G3 patterned magazines.

To accommodate longer than SAAMI-spec match ammunition, this magazine may not drop free from all makes of lower receivers.
 
OP
Mk3Mstr6Mchne0
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Oil it...This is an AR and AR's like to run wet. That BCG looks very dry as does that entire gun. wetter is better ;)

oil up the mag catch and make sure it moves freely but springs back as it should.

on your mags make sure the followers are springing up as they should and not sticking or jamming up.

make sure the magazine fully locks into place.

Also what brand and generation is your upper receiver, lower receiver, and bolt carrier?

By generation I mean is it DPMS gen1 or DPMS gen2?

From the Magpul website regarding the PMAG LR/SR Gen M3 magazines.
This issue occurs even when drenched in oil
 

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