If it hasn't been mentioned, when the mag catch nut is reinstalled, it should be adjusted so that the plunger is flush with the frame or slightly below the level of the frame.
Naturally, the mag catch must function normally in securing and releasing the magazines when installed.
Occasionally a magazine nut may feel rough in operation. If it's an older combination of parts it may be due to oxidation and corrosion on the spring and inside the spring hole. (When someone allows a gun to be submerged, and doesn't tell anyone about it for a year ... it can be annoying.) If it's roughness occurring with new parts, armorers are taught to deliver an impact to the catch nut with a plastic mallet to see if that 'frees up' movement and removes the roughness. I can only remember having to do that a handful of times over the years in older 3rd gen guns. (Newer guns and parts have some much better tolerances.
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Every once in a great while I've come across a combination of new mag catch parts (mostly a mag catch body or nut) that just didn't work right in a particular frame, or wouldn't hold a mag securely. The last one was in a recent; production 4513TSW. The easiest solution (which worked) was to try a different set of mag catch parts in that particular gun.