Daniel Defense MK12 & PMAG Issue

In this post, I review an HRF RCM magwell for my Daniel Defense (DD) MK12 in this article. After the installation, I noticed an issue with magazines snagging when inserting, especially at a certain angle. For full disclosure, this happened with Magpul Gen 3 PMAGs, which I have a majority of.

When I experienced this with one magazine, I tried multiple Gen 3 PMAGs, and all snagged at a specific angle when inserted. I noticed a Daniel Defense mag did not snag like the PMAG.

Let the forensic investigation begin!

Starting with the MK12, I noticed a flat edge inside the magwell on the finger guard. Circled in red in this photo.

Looking at the PMAG, there's a flat edge on the back of the mag. Circled in red in this photo.

I tested inserting the PMAG many times at many angles. The PMAG would snag (get stuck) at the magwell entry at one slight rearward angle. This angle was natural when holding and inserting the PMAG. It would take a lot of practice to insert the mag straight, avoiding the angle that gets stuck. A lot of practice, almost robotic-like.

This may not be practical in a life-or-death situation, competition, or timing scenario, especially with having a flared magwell.

I noticed the Daniel Defense magazine was not snagging at the same angle. This photo shows that this mag does not have the edge on the back like the PMAG.

What to do

After performing a lot of testing with the PMAG and DD mags, it was clear that the edge of the PMAG was getting caught on the edge of the finger guard on the MK12.

The PMAG or the MK12 has to be addressed, but which one? I decided not to smooth the edge on the PMAGS, as there are many of them, any new ones, or if I borrow some. Instead, I will smooth the edge of the MK12 finger guard.

Smooth up in ya!

I'm a rock and metal fan and like this song by BulletBoys, but it's fitting, given the result. Read on.

Note: The following was performed on my rifle, and I'm not suggesting any modification to anyone else's. If you decide to do this yourself, do so at your own risk!

So I don't get pieces or dust in the action, I taped the magwell (with painter's tape).

Using a small file, I smoothed (rounded off) the edge of the finger guard. It didn't take much work, but I had to file evenly and at the correct angle. The angle of the file was very low, just above the RCM magwell.

Once the edge was filed off, I polished it with 500-grit sandpaper. I cleared off the taped area and used a piece of tape against the smoothed area, like a tack cloth, to clean it. Then, I polished the edge with gun oil (I use synthetic oil by Liberty Gun Lube).

Using the same PMAG, I tested the smoothed edge, and well, like the song goes!

No more snagging of the PMAG.

Remember:

1. Always keep the firearm pointed in a safe direction.

2. Treat all guns as though they are loaded.

3. Keep your finger off the trigger until you are ready to shoot.

4. Always be sure of your target and what's beyond it.