I'd undoubtedly check out them. There is not purpose that they would not work just fine inside your Beeman. I've had great luck with RWS pellets in all of my airguns (Hatsan, Crossman, Benjamin and so on.). I would try a tin and find out how your Grizzly likes them https://spencerhteoz.blogozz.com/35058428/the-5-second-trick-for-super177