Polymer 7.62x39 AR Mag

[Airborneguy]

Starting this thread to detail a project I am going to work on. My goal is to turn a 20rd .223 Pmag into a 10rd 7.62x39 mag that feeds reliably.

My research so far points towards removing the guys then filing down the ribs on the inside and modifying the follower. I am hoping though to modify a C-Products follower to fit the mag instead. I'll take pictures as it goes along.

Thing is, I love 7.62x39 in the AR and hate metal mags for it as they tend to ruin the brass quickly.

If anyone has any tips, please post.

 

[meketrefe]

You will need to open up the lips too. They have different radius. I am not sure how to do that with the polymer.

 

[Airborneguy]

Seems to me like the problem is mostly the tilt of the follower. I'm also going to cut some down a little off the front because the tips of the bullets seem to hang up there a bit.

As soon as I get the mag I'm going to modify I'll take some pictures.

 

[Clipazine]

I dunno man. 7.62 has a pretty pronounced tapper to them. not gonna be easy. looking forward to the results.

 

[turbobike]

[QUOTE="Airborneguy, post: 57931, member: 6"
Thing is, I love 7.62x39 in the AR and hate metal mags for it as they tend to ruin the brass quickly.
[/QUOTE]

I also like the 7.62x39 in my AR. I concur, you're absolutely correct the brass does get beat-up in the SS mags. If I find a 20 round Pmag, I'll try one of my Magpul 7.62x39 followers in it and also trim the lips and then see how it works.

 

[Airborneguy]

If I find a 20 round Pmag, I'll try one of my Magpul 7.62x39 followers in it and also trim the lips and then see how it works.

Are your referring to their AK mag followers? I was going to get one but then I compared the ASC and Cproducts followers to the Magpul .223 one and found that on top they're basically the same. The major differences seem to be with the legs.

I'm thinking that if I cut the front leg completely off, cut the back leg down about half, and create an angled wedge to direct the soring pressure more towards the rear, I may have something better. Looking at the spring in my ASC mag, it appears to be bunched up and angled to put more pressure at the back. If it fits, I'm going to just use that spring, maybe with a flat block to lift it if it is not high enough. Does that make sense?

 

[meketrefe]

[QUOTE="Airborneguy, post: 57931, member: 6"
Thing is, I love 7.62x39 in the AR and hate metal mags for it as they tend to ruin the brass quickly.

I also like the 7.62x39 in my AR. I concur, you're absolutely correct the brass does get beat-up in the SS mags. If I find a 20 round Pmag, I'll try one of my Magpul 7.62x39 followers in it and also trim the lips and then see how it works.[/QUOTE]

They might put marks on the brass but it is cosmetic and it should not impact the actual performance or life of the brass.
A brand new magazine might have some sharp edges but nothing a stone or bit of emeri cloth could not fix in 2 minutes.
I would be more worried about the SIG and AK extraction that puts huge dents in the mouth and body respectively.
Colt GI aluminum magazines continue to be the best magazines for the AR15 after upgrading the follower.
they might be ugly and beaten but they are utterly reliable with the modern followers like magpul.
A few weeks ago I read a review where rental ranges have these mags with millions of rounds of service. Let me see
if I can find it.

 

[Airborneguy]

Got my Magpul mag today. I thought I ordered a 20 but it's a 10. Oh well.

So first I cut off the front rails of the ASC follower using a heated knife. Here's a pic:

 

[Airborneguy]

Ok so step two was the hardest and took the longest. I had to cut down the remaining side rails, trim the front so it could clear the interior rail that Magpul uses, and thin out the thick part in the rear just a bit so it would fit the shape of the Magpul body. This was accomplished with a mix of sanding and trimming with the hot knife. None of this looks pretty, but after at least an hour of work, I got the follower to the point where it would fall through the mag to the top, as the original Magpul .223 one would.

 

[Airborneguy]

Sorry for the messed up pics. As you can see, I also cut a notch in the front to match (as best as possible) the front interior rail.

At this point, I could assemble the mag fully and it would hold three rounds and feed them into my rifle.

I noticed that the first round would be below the lip of the mag if I loaded 4, so I trimmed the front of the mag body just enough to clear it when loaded with 4.

 

[Airborneguy]

I wasn't happy with how much tension was on the follower still so I cut on rung (?) off of the spring. This was a bitch! Those springs are tough. But I finally found a cutter strong enough and took one off, slightly lessoning the tension.

 

[Airborneguy]

So as it stands I can easily load 4 rounds and they fed perfectly (manually of course). I wish I had time to check this before thursday when I got hunting again, but I can't make it to the range tomorrow. I'm going to bring an extra mag just incase I run into trouble with it.

So far I am happy with the results, but this took longer than I thought and required much more modification than expected so it will probably be the only one I do. I may try to get my hands on a Magpul 7.62 follower from an AK mag to see if I can do something with that, but it appears this set up will accomplish my needs.