The M-11 firearm. Perhaps the only gun that needs instructions for using standard box magazines. Because of the shoddy manufacturing of these guns, there are three items that you need to check before using your new ZMAGs:
1. The ZMAG is designed for the standard SWD grip. If you are using the excellent Lage grip—and purchased it before December 2013, you will need to clearance the grip for the mag stop on the ZMAGs. (Lage grips purchased after that date are modified at the factory for the ZMAGs.) See the picture below for an example of the notch you will need to file on the inside front of your Lage grip to accommodate the ZMAG’s mag stop.

2. Next, you will need to check for obstructions in your magazine well. Any welds or other protrusions that are thicker than .010” (the thickness of two sheets of paper) can hang up the ZMAGs when inserting or removing them. See the weld that’s been filed down in the picture below:

3. Lastly, the ZMAGs are designed for variances in mag release and vertical bolt location (upper receiver to lower receiver fitment). See post below. As such, there are guns that will “wear” the very tops of the feedlips the first few times you rack the bolt. This self-clearancing is normal—and by design.

The M-11 by their nature are very imprecise firearms. We had to design the ZMAGs with this in mind—and incorporate this self-clearancing feature. If your magazine looks like the one below after racking the bolt a few times, it is completely normal.