Removal of the whole mag catch assembly & body requires removal of the grips.
However, removal of just the mag catch nut (button), plunger & spring can be done with the grips on the EMPTY gun, but it's best done with a nickel (right thickness) under the right end of the mag catch body (to keep it still and unmoving while working on unscrewing and then reinstalling the nut on the opposite end). It needs to be done on a flat, firm surface (not the wife's nice kitchen table, BTW).
The mag catch plunger is depressed with a small pin punch (1/16"), holding it below the bottom edge of the mag catch nut. The top of the plunger rests within 1 of 2 machined recesses on the underside of the mag catch but, located 180 degrees apart. This is how the spring-loaded plunger "locks" the nut in place.
As the plunger is being depressed and held down, the nut is unscrewed (some armorers file the tip of a slot screwdriver to make a spanner wrench for this task).
As the nut comes off the threaded end of the mag catch body, the plunger is now free to launch itself up and into your eye, and/or then across the room. Wear safety glasses. Try not to let the pin punch tip slip off the plunger. The plunger is small and can hide in the damndest places.
Sometimes a bit of corrosion/oxidation on the spring, or within the spring hole, can cause roughness when the spring is compressed. So can a broken spring (not as common as oxidation). The spring can be wiped down with a patch lightly dampened with your favorite CLP, and the spring hole can be blown/cleaned out, as well. Wear those safety glasses.
Reassembly is the reverse order of removing the nut, plunger and spring ... except trying to get the threads to catch (without stripping the nut and/or the mag catch body threads)
while holding down the plunger & spring with the itty bitty pin punch, can sometimes allow a moment's inattention to send the plunger up into your eye (
not again !?!), or off to parts unknown. PATIENCE and caution are prudent. Don't load up on caffeine beforehand.
Now, the mag catch & its nut have to be adjusted for the catch to do its job right. This is because it changes the length of the assembly and how far it can move. This usually means the top of the plunger ... once it's been popped up into one of the slots underneath the bottom edge of the nut ... ought to be either flush with the outside of the frame, or slightly below it. This is when the mag catch ought to hold the mag, after securing it smartly in place ... and then also release the mag when normally depressed.
Now, the "smoothness" consideration.
Believe it or not, armorers are taught that they can sometimes take a
plastic mallet (NOT a ballpeen hammer, brass hammer, etc) ... one of those clear yellow plastic mallets ... and briskly whack the mag catch nut (button) a couple of times. Snapping it down into the frame with a speed and sudden force your thumb can't match. Apparently, it's amazing what the judicious application of some sudden and briskly applied "whacking" force can do to some occasional burred edges inside the mag catch assembly.
Hey, I didn't
write the armorer manual or come up with this stuff myself. I just collect copies of it from armorer classes.
All joking aside, sometimes the plastic "mallet whack" has done the job ... other times cleaning out the spring hole and a rusty spring has done the job ... and sometimes I've found an occasional mag catch assembly that required replacement in order to resolve some operation issue caused by the wrong tolerances coming together.
Some thoughts ...
Don't try to fiddle or tinker with firearms if you don't know what you're doing. Seriously. I'm NOT recommending anyone try this stuff. I'm only explaining how armorers are taught to do it for the purpose of this thread discussion.
Don't put an eye out, or lose parts which are under spring tension and unexpectedly take flight during a moment's inattention (a couple of bad ideas even if you do know what you're doing).
