MK620 Magazine problems.

I just received an extra MK620 (Short) magazine for my MK9 & it will not load more than 4 rounds of ammo. My original magazine that has had more than 400 rounds loaded has functioned flawlessly. I like to rotate my carry magazines to keep the springs in good condx. This new mag has a much stiffer spring than my original mag and will load no more than 4 rounds and the fourth is so hard to load that I don't think it will feed. Has anyone else had problems with Kahr replacement mags? My original mag will let me load 5 rounds but the last one is hard to load. I have a feeling that the magazine spring is the wrong one for this mag. I am calling customer service tomorrow to see what they say. The darn mag is not cheap & compared to the fit,finish & overall quality of the weapon it sucks.

Larry Woolis
NRA Life/Patron member.
50 + years of NRA membership.