Joe Klug, I've posted this before-- and the above posters are correct-- you can use 92S, 92F, and 92FS hi cap mags IF you cut the magazine release hole in those mags, to EXACTLY match the hole in the Cougar mag. I have seen an LEO armorer do it with a milling machine and it worked perfectly.
I wouldn't try it with a Dremel tool, but then I'm not good with one. If you have a milling machine and calipers, it's not at all difficult. Or, if you have a friend who has same. Good condition, hi cap Beretta mags are still easy to come by at the gun shows, at least in my area.
Best of luck. J.B.