Author Topic: 20-round AR-15 mag mod  (Read 272 times)

Big Frank

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20-round AR-15 mag mod
« on: April 14, 2024, 12:53:08 AM »
I already filed down the tabs on the bottom of the mags so I could get Magpul self-leveling followers in them. I recently found out, after I bought another 3-pack of them and having one left, I already had 2 left of a previous 3-pack. So now I have a whole package of them. And I have Tubb Precision AR-15 17-7 SS magazine springs - 30 Round in them, which due to the flatwire design will also fit into US GI 20 round magazines. They come as singles, 3-packs, and 5-packs. I put the Magpul Ranger Plates back on them, and put the Samson Manufacturing Multi-Mag Holder back on instead of the cut-down Choate M-16/AR-15 Magazine Connector I was using. I had to stagger the mags to clear the ejection port cover with the Multi-Mag Holder, because the mags are so close together. That makes the whole assembly shorter than a 30-round mag, but looks longer in the picture. I can grab them by one of the Ranger Plates to pull it out of my mag pouch without using a foam rubber stress ball in the bottom of the pouch to raise them up, as previously.

Now, here's what I did to modify the magazines. Since the mag body is straight and the rounds are tapered, the bullet noses were hitting on the front of the magazine until it was down to the last 10-12 rounds. I only had 15 rounds in them anyway, because the Magpul followers cut down on the available space, and the Tubb mag springs don't help that situation. But the first few rounds were still pointing down, so I took the mags apart and beveled the front wall all the way across, at about a 45 degree angle. I made feed ramps on the mags and they should work, but I won't know until I try it out, probably this summer. Wish me luck.

I used a flat file that was nearly as wide as the space I had to work in, and angled it left and right to work my way all the way across instead of just filing the middle. I filed them down until it started to raise a burr on the edge, then used a Swiss pattern file to file it smooth, and finally filed the burr off with it. I don't remember if I sanded them down at all, but, the small file left a surface nearly as smooth as stoning does. I just remembered I have a stone I could use on them. I found it next to the house in the dirt when I banked it up several years ago. After the edge was safe to handle, I cleaned the mags by pulling half of an old towel through them a couple times, and reassembled them. The right-hand mag is about 7/8" lower than the right-hand mag, just like the pair of ETS Carbon Smoke GEN 2 AR15 Magazines, 30 Round, w/ Couplers I have. The blade of my Pocket Samurai knife just fits between the mag coupler and trigger guard, and between the right-hand mag and end of the ejection port cover detent.
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