I am gonna say yes. Beretta sold the machinery for the Cougar to Stoeger so they should be interchangeable. Stoeger does not make magazines for the Stoeger Cougar. The Stoeger Cougar is actually sold with two "Beretta Magazines"...made in Italy.
"There is no hunting like the hunting of man, and those who have hunted armed men long enough and liked it, never care for anything else thereafter." - Hemingway
The greatest ignorance is to reject something you know nothing about.