I'd personally unquestionably test them. There is certainly not motive that they might not operate just good within your Beeman. I've experienced superior luck with RWS pellets in all of my airguns (Hatsan, Crossman, Benjamin etcetera.). I would consider a tin and find out how your Grizzly likes them as https://super17712222.ssnblog.com/34975438/a-secret-weapon-for-super177