New to CZs with a magazine issue

[sidreilley]

Hi guys,  Just got my first CZ, a used 85, and I find it a natural shooter, there's just one problem; the magazines. I ordered a couple of new Mec-Gars as it only came with one mag and I was quite surprised to find that they won't go into the mag well. The original mag is a tight fit but the new ones won't even go all the way in. I have since been told that the mags on pre-Bs are different but I'm wondering if it is possible to enlarge the mag well by stoning it a bit. Doesn't look like it would take too much. Has anyone done this before and has any words of wisdom?  Thanks.