NOT KNOWN DETAILS ABOUT SUPER177

I would absolutely test them. There is certainly not rationale that they'd not function just high-quality in your Beeman. I have experienced very good luck with RWS pellets in all of my airguns (Hatsan, Crossman, Benjamin etc.). I'd personally attempt a tin and find out how your Grizzly likes them as all guns appear to have their favored pellets.Um