I'd personally unquestionably try them. There is not reason that they would not work just fine with your Beeman. I have had 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://super17723222.newbigblog.com/42288028/the-smart-trick-of-super177-that-nobody-is-discussing