We Now Have Windowed 15 Round .40/10mm Magazines for Rock Island Armory High Cap FS A2 Pistols

I’ve written in the past how I have a new RIA 52009 High Cap 10mm and it’s virtually impossible to find the original OEMP164015B mags right now. Seizing on this business opportunity, I started converting Mec-Gar MGP164015B for use in the RIA double stack/staggered .40 & 10mm pistols (they share the same magazine). Things were going great until all sources of the Mec-Gar MGP164015B dried up too (thank you panic buying). So what to do?

8/25/2023 – We do not carry the Windowed mags at this time but we do have three different capacity magazines for the RIA 10mm/.40 S&W – 10, 15 and 16 round – click here to open that page of the store in a new tab.

I started digging and found out that the Mec-Gar MGP164010B is the exact same magazine except Mec-Gar used a hydraulic press to form dimples in the tube to stop the follower at 10 rounds for folks with Para 16 pistols in areas that had a 10-round limit.

I brought in a bunch of the 10 round mags and converted them for use in the RIA pistols. Then, the supply of the MGP164015B mags dried up and I decided to figure out how to convert the MGP164010B magazines for use in 16 round RIA .40 and 10mm pistols.

To make a long story short, you drill out the dimples, remove the burrs from the inside of the tube and then sand it down. That’s why the mags have 3/8″ windows drilled in them. The fact the magazine bodies were tempered steel definitely made life interesting when it came to the drilling and deburring operations.

Here’s a Mec-Gar 20 round magazine that is about to get the dimple drilled out. I made the jig to securely hold the magazines during the drilling operations.

Folks, I have gone through a ton of dummy rounds prototyping and now testing the magazines. I also use a MagLula to help me load every magazine and with 15 rounds. I am testing that the load and feed smoothly. If they do not then that would tell me something needs more work in the tube.

Bottom line, I was able to make more of the RIA high cap (HC) 15 round magazines. They all have a Teflon dry lube internally and Dawson Precision +100 black base plates. These are really nice and extend just a hair below the funnel allowing you to positively seat the magazine in the weapon.

The Dawson +100 base plate fits very nicely. They make other lengths that you can buy directly from them if you are interested.

Here’s a close up of the Dawson +100 base plate. Note, these are Para magazine style base plates.

In Conclusion

Now you know why we have windowed magazines for sale (I had to drill out the dimples). If you are interested, click here to go to our online store and you can see what magazines we have in stock right now.

Note, I have to buy all of my parts – nothing here was paid for by sponsors, etc. I do make a small amount if you click on an ad and buy something but that is it. You’re getting my real opinion on stuff.

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