tactical sport magazine doesn't take last round

[Philippecz]

Hi guys

I have a problem with 2 of my tactical sport (9mm) magazines.
When I shoot a full or half magazine, the last bullet doesn't go into battery and the slide stays open with one round in the magazine.
Does anyone know what may be causing this problem?

[Grendel]

The last bullet is walking forward and nudging the slide catch. Check the catch for brass marks.

Try (in order of difficulty/expense):

Different (shorter OAL) ammo

New mag springs

Filing the slide catch a little at a time until the rounds don't contact it.