9mm ar15 narrel feed cone

KY DAN

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Jan 10, 2019
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I am having issues feeding rounds in my 9mm ar build.

Users colt style mags

Kak mag block installed and locked down with set screws.

Ar15 carbine buffer spring

Kak 10.5 Oz buffer

I see where the funnel can be recut to be larger and at a more receivable angle.

I looked at 11 degree target crown and realized they have to be set at 89 degrees to be 11 deg when measured from the appropriate angle plane.

I want to cut the new funnel at 62 degrees and cut the same way as a 11 deg target crown.

I think this makes 124 degree angel

What is the thoughts?
 
is the bomt designed for a colt as a glock type isn't compatible

I am unfamiliar with bomt so I can't answer that , could you please explain?

Everything I purchased was for a colt style operating base.

1 time a 20 rd magazine I will get a jam where the cartridge hits the face of barrel.

It's usually the last 3 rounds

The brass is ejected 3 o clock postion
 
Can you post pics of the feeding cone ?

And I would polish all the feeding surfaces first.

The 10.5oz buffer might be to much.
 
I am unfamiliar with bomt so I can't answer that , could you please explain?

Everything I purchased was for a colt style operating base.

1 time a 20 rd magazine I will get a jam where the cartridge hits the face of barrel.

It's usually the last 3 rounds

The brass is ejected 3 o clock postion
Stupid auto in-corrected me again


BCG

Hopefully fixed this time


The BCG is different on the Colt and glock styles. Springfield Armory uses Colt style bcg's and mags in their pcc. Not sure what ruger uses?
 
Seeing where it does feed and eject until it gets down to the last few rounds, I'd say it's the mag. Colt stick mags I'm unfamiliar with other than they're straight treat them like 1911 single stack mags..... as they are the problem! What brand is the mag as some brands aren't as reliable.
 
Seeing where it does feed and eject until it gets down to the last few rounds, I'd say it's the mag. Colt stick mags I'm unfamiliar with other than they're straight treat them like 1911 single stack mags..... as they are the problem! What brand is the mag as some brands aren't as reliable.


Mag brand is AR stoner

All mags tested of this brand seem to do this, I can pull the trigger as fast as possible and gun works until last 3 rounds of ammo.

That is when a round will plant itself in the face of the barrel.
 
Either the follower or spring seems to be the issue. I've had similar issues with Promag's. Disassemble the mag and check. Spring might not be strong enough to reliability feed the last 3? Follower could be dragging.? That is a double stack or a single stick mag?
 
Load 2 or 3 and shake or bounce the mag and watch how the ammo reacts. I don't own many single stack mags (de 44mag and 50ae only), but they're short unlike stick mags.
 
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Something isn't playing well between your bolt, magazine and feed ramp as you get to the "bottom of the stack" of cartridges. Especially if the first 17 rounds feed fine, it isn't the feed cone angle. Do you have any magazines that do feed OK all the way to the last rounds?

Get 3-4 dummy rounds and cycle them slowly, trying to observe the interaction of the various parts involved. Your magazines could be riding a bit low, the bolt might be hitting the base of the cartridges in a way that's tipping the nose down, the bolt hold open could be bumping into the bolt and slowing the movement, just as some options I can think of off the top of my head. Be patient, go slowly and you'll find the source of the issue.

And yes, once everything is dialed in, it should feed dummies when hand cycled without letting the bolt run forward at full speed.
 
I shot a mix of lead rn, jacketed rn, xtp 115 gr, and 150 grain lead swc.

This is what is so confusing, the carbine feeds any ammo you can find.

First 17 goes well and after that it's stoppages
Try stretching the spring in one mag for more spring pressure, just as a temp fix to test fire 3 or 4 rounds.
That's simple, cost nothing, and all parts remain "stock"
jmo,
.
 
FWIW, there are 2 styles of Colt Pattern 9MM mags... the ones you are using ( ASC ) and MetalForm made ones.

Example...
https://www.midwayusa.com/product/1006330269?pid=348644

Lots of Colt Pattern 9MM PCC's prefer one or the other.
With the MetalForm ones... you MUST clean the interior of the mag body and the follower, wiping down the spring as well.

I would make sure your ASC ( ArStoner ) ones don't have a burr inside the mag body.

And then DriFilm lube the interior of the mag body, the spring, and the follower.
 
Either the follower or spring seems to be the issue. I've had similar issues with Promag's. Disassemble the mag and check. Spring might not be strong enough to reliability feed the last 3? Follower could be dragging.? That is a double stack or a single stick mag?
I agree with this. If you were having a compatibility problem, I would think that it would manifest itself when the magazine is the hardest to feed from, which is when it's fully loaded.

If the last few rounds won't feed, they are likely nose diving.

Which barrel are you running? If it is of recent manufacture, the feed ramp likely isn't the problem.

Get some metalforms or maybe try a cproducts magazine. Better yet, get some new springs from Wolff.
 
Have you tried loading less than a full magazine? Like 5 less than full. When you do that, will it feed all of the rounds?

I'm still thinking it might be a spring issue.
 
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