NOT KNOWN DETAILS ABOUT SUPER177

I would undoubtedly check out them. There's not explanation that they would not get the job done just high-quality in the Beeman. I have had good luck with RWS pellets in all of my airguns (Hatsan, Crossman, Benjamin and so on.). I'd personally test a tin and find out how your Grizzly likes them as all guns seem to have their preferred pellets.Umar