as pblanc pointed out the Stoeger is built on the same tooling as it was when it was made under Beretta, They discontinued it under the Beretta brand and started selling it under Stoeger (Turkey mfg) which they own.
The cougar is a nice gun, I've got a 9mm (8000 model) and the fit and finish is excellent.
Magazines can be a pain to find and costly when you do.
The bodies are exactly the same as a Beretta 92 mag the only difference is the mag catch notch.
On a Cougar the notch is higher up on the body.. You can insert a Cougar mag in a 92 and it will lock in place before it's fully inserted.. and if you do the reverse with a 92 mag it just never locks in place.
The solution is to just cut a new notch in the body.. it's not difficult with a dremel tool, barely cut the slot, then finish up with needle files.
It does not take long, most important thing is making sure your measurements are correct before you make the cut.
You can also do this with Taurus 92 mags, in fact if you do it to Taurus mags you can use them in both guns cause the Cougar slot is small enough that the bigger Taurus catch will just glide past it.
Mec-gar does not make mags for the Cougar, what a pitty, so if you want 18rnd mags you'll have to convert them your self.
I don't recall who but there use to be a guy on the Beretta forum that would convert mags for a fee, He had a jig so I hear the work was very professional.. but you can do it your self free hand with the pre mentioned tools.