I'd undoubtedly try out them. You can find not reason that they might not work just fine in your Beeman. I've experienced great 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 https://finnxnany.blogocial.com/the-fact-about-super177-that-no-one-is-suggesting-71733001