Yup, Specnas are one of the worst brands for mag compatibility, except for all the other brands.
Issues can usually be ameliorated in the field by wiggling and slamming the mag in, but you might get some mags that just wont fit or feed. This can almost always be sorted by either filing/sanding, or shimming, the mag as appropriate to line it up with the feed tube. Or if you have a lot of mags that need sorted, it can make more sense to shim inside the magwell instead. The fuzzy side of self-adhesive velcro tape is popular for this, or just use duct or electrical tape in a pinch - you could also stick a strip of plastic on if you need a big adjustment, e.g. piece of cable tie.
If you do run into problems, then find a mag that does feed, and put it side-by-side with the bad ones. Eyeball and measure them up, and note how the feeds in the top of the magazines align (or don't align) - that will tell you whether you need to remove or add material to or from the front or back or the bad mags to make them match up and feed gooderer. Examples: