All mags have the same result

i had the same problem with my 30 the magazine has to be used a few dozen times. pick up lula mag loader this will help getting that last round in, and yes you have to use a little force but it will eventually work itself in.

Butler Creek 24222 Lula Magazine Loader for 9mm .45 Caliber

on my 30 with the oiginal mag fully loaded i need to firmly seat the mag with the 2 new mags i bought i need to hit the bottom of the mag to seat it and the slide is very hard to rack with the newer mags in it no problems when shooting it also when i first got the new mags i could only load 9 rounds untill i let the mags set for a week loaded with 9 rounds then i was able to load the 10 th rounds now no problem

It's not the mags. I have had them and used them multiple times for over a year and have never had an issue getting 10 rounds in them nor getting the mag seated when full until now (seating full mag with slide forward). I have always stored them full.

do you have any Glock Armorers in your area ?at the locial gunshows i go to there is 1-3 Glock Armorers that have tables they are aways happy to look over any of the glocks i've owned for free. if after shooting it if it still has the problem i would have a Glock Armorer look it over