NOT KNOWN DETAILS ABOUT SUPER177

I'd personally unquestionably try them. There's not motive that they might not get the job done just great in your Beeman. I've experienced fantastic luck with RWS pellets in all of my airguns (Hatsan, Crossman, Benjamin etc.). I would try a tin and find out how your Grizzly likes them as all guns appear to have their beloved pellets.The RWS Superd