I would undoubtedly try out them. There is not reason that they would not work just fine in your Beeman. I have experienced good luck with RWS pellets in all of my airguns (Hatsan, Crossman, Benjamin and so forth.). I'd try a tin and find out how your Grizzly likes https://super17766655.shotblogs.com/super177-things-to-know-before-you-buy-49958261