Mean Arms came into the Pistol Caliber Carbine (PCC) market with an interesting idea. They made a 9mm insert for Magpul Pmags, called the “EndoMag”. This eliminates having to use a special lower receiver or magazine adapter. I was intrigued after we discussed them on the Gun & Gear Review Podcast. Mean Arms kindly sent one for review.

The Endomag is not your standard magwell adapter. First up, it goes inside a Gen 2 or 3 Pmag body. Just take your Pmag apart and set your spring and follower somewhere. Now, depending on where you live, cut the Endomag to the required magazine capacity. It has marks for 15, 20, and 30 rounds and comes in a 10 round configuration. The included instructions tell you how to do this and it is super simple. I cut mine to accept 30 rounds. Then all you need to do is slide the Endomag assembly into the Pmag body and install the floorplate. It is now ready to be used.

Before using the Endomag, it is recommended that you break it in. Basically, it involves testing to make sure the mag body doesn’t rub the bolt. Then testing cycling, by hand, with the Endomag installed. Again, the instructions are very useful here. I could feel the bolt rubbing a little on the one they sent me. I just did as instructed and have had no issues.

The Endomag has some great benefits, and a few that leave me wanting something else. I love the ability to load rounds just by pushing them down, much like a standard AR magazine. This is because the Endomag is a double column, double feed magazine, much like the Colt 9mm style magazines. The Endomag also features a last round bolt hold open feature. My biggest complaint about the Endomag is the built in ejector. It functions great, but takes some training to unload the firearm. One has to cycle the bolt back by hand to eject the live round. Then while the bolt is back, you have to drop the magazine. If you drop the Endomag out before cycling the action, the round will not eject, and thus just go right back into the firing chamber. Like I said, this is a training issue, but during a competition this could confuse some people and maybe even cause an unsafe condition. Besides this training issue, the Endomag doesn’t require any other learning curve. It is the same size as a standard magazine, therefore it fits in all your gear. All the rifle’s controls will also be the same, especially the magazine release button. I also noticed that the magazine spring, that Mean Arms uses in the Endomag, looks very much like the spring that came out of the standard Pmag. So much that I would guess it is the same spring. The EndoMag also lets one “try out” a PCC without having to purchase a lower receiver or magwell adapter. Of course you would still need a complete 9mm upper.

I used the Endomag a lot. As expected, it ran like a champ. If I had a failure, it was minor, because I don’t remember any. One of the nice features about installing the Endomag in a Pmag body is that you can mark the Pmag with “9mm” in the dot matrix! That way you have a better chance of not getting your magazines confused. As far as training with the Endomag, I give it a thumbs up. 9mm is cheaper than 5.56/223, and has about the same felt recoil. So you can get some good training in, for cheaper.

Mean Arms has a good idea with the Endomag. It has some decent features to aid in training. Goes into a magazine body that you probably already have, and works fantastic. I just had to get over the ejecting a round before dropping the magazine. If you think the Endomag is for you, go give one a try, they are inexpensive enough to see.