M4 Mid-Cap Magazines Constantly Jams

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M4 Mid-Cap Magazines Constantly Jams

I've been playing with my M4 mid-caps for about three years now. And they have been working great until last month. They have started jamming a little more and more over time. Last month, they have jammed all time time. And this week, I have found that they jam as soon as I load them up with BB's. And it's the same with all three brand of mid-cap mags I use: Asia Electronic Guns, G&P, and Magpul PTS EMAG. They have all failed at the same time,so I guess their internals are all very similar. So I have taken them all apart to fix them. And I will explain how I got them all fixed in this post.

What I learned from taking them apart is that the BB's are all double stacked internally for maximum capacity. But the double stack is not staggered. At the mouth of the magazine, it's tapered into a single round mouth. And there are two slightly staggered inclines on two sides to merge two lanes of BB's into one. The staggering is so slight, they seem not staggered at all. The BB's are pushed up in the magazine with a spring and a plastic head (shown in the photo below).

Over years of use, the BB's created grooves in the inclines that causes them to jam every time.

Attached Image:

IMG_20170707_215146.jpg

Matt
Sun, 09 Jul 2017 21:02:20 -0700

I found on the following posting where someone mentioned cutting a slant into plastic spring head:
http://www.airsoftsniperforum.com/35-sidearms-optics-gear-ac . . .

That made sense to me, because with a proper slant, the double stack could become staggered. The trick is what is a proper slant?

I cut one of the heads using a large wire cutter and pliers (see photo below), based on what I think will work. I put it back and it worked. The magazine feeds flawlessly.

Attached Image:

IMG_20170707_215514.jpg

Matt
Sun, 09 Jul 2017 21:19:23 -0700

But cutting the head right isn't always easy to do. The shape of the G&P spring head is almost impossible to cut without messing up. The Magpul PTS EMAG has articulated spring head that could not be cut at all.

I found that the spring at the head end is a spiral. So the mags actually works better with the spring without the head. After pulling the head off and putting the spring back into the mags, the mags actually worked flawlessly.

My only concern is that over time, the BB pressure will possibly change the spring shape. And that potentially could cause the BB's to get trapped in the spring.

I sent a message to Airsoft3D, suggesting that they make a slanted replacement head for mid-cap magazines. They said they will design one for testing soon.

Matt
Sun, 09 Jul 2017 21:48:04 -0700

Thank you, Matt, for sending us your suggestion. We have completed prototyping and testing of the feeder head that never jams. They are now available for purchase on our storefront here:
https://www.shapeways.com/shops/airsoft3d?section=Magazine+A . . .

Good luck. And hope you'll never have a jammed BB magazine again.

Attached Image:

Airsoft Magazine Feeder Head.png

Airsoft3D
Wed, 30 Aug 2017 03:21:55 -0700

I tested an orange version of the magazine feeder head. It was easy to attach to the spring.

I noticed that the spring is bent from being used on the airsoft field without the feeder head (see photo below). So I would definitely not recommend using the magazine without a feeder head.

The Airsoft3D magazine feeder head works flawlessly. So far, no BB jams.

Attached Image:

Orange Version on Spring (Small).jpg

Matt
Sat, 16 Sep 2017 22:00:28 -0700

The orange version also allows me to see when the magazine is empty or containing airsoftBB's; my BB colors are tan or black. The original feeder head is black. And the new feeder head gives me the confidence that there is no jamming when I can see it clearly.

Attached Image:

Orange Version Magazine (Small).jpg

Matt
Sat, 16 Sep 2017 22:02:19 -0700

We have now completed the magazine feeder head for Magpul PTS PMAG / EMAG airsoft magazines. It should also work for any similarly designed magazines. We tested it on our EMAG 30 and it produced no jams. It's now available on our storefront:
https://www.shapeways.com/shops/airsoft3d?section=Magazine+A . . .

Attached Image:

PMAG EMAG Feeder Head.png

Airsoft3D
Mon, 18 Sep 2017 15:08:33 -0700

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