NOT KNOWN DETAILS ABOUT SUPER177

I'd certainly test them. There is certainly not motive that they might not work just fantastic in the Beeman. I have had very good luck with RWS pellets in all of my airguns (Hatsan, Crossman, Benjamin and many others.). I would consider a tin and see how your Grizzly likes them as all guns seem to have their most loved pellets.Umarex twelve Gram C