I got 2 of the coveted 25 round mags. The ones for the Plinkster not the tactical. They inserted fine but releasing wasn't good. They have a plastic lever that pushes on the mag release of the rifle. Pressing it would lower the mag a bit and then it catches again. You would have to jam your finger between the mag and rifle and press the release again to remove the mag.
Looking at the metal mag release on the rifle it has a second bump on it that catches the mag. I ground this down flush. Next the plastic button on the mag didn't have enough travel to press on the metal release sufficiantly. Remove all screws and take the mag apart. There are 3 places where the travel is limited on that plastic lever, grind them down and you increase the travel so now you can push the lever and release the mag in one smooth motion as it should be.
Not sure why Mossberg made this system this way, but now both mags work.
Also with any semi-auto .22 add no oil to the bolt or action so it runs dry and doesn't gum up. I've had no FTF, FTE, and only 1 FTF (ammo's fault)