I might absolutely test them. There is not motive that they would not do the job just fine within your Beeman. I have had excellent luck with RWS pellets in all of my airguns (Hatsan, Crossman, Benjamin etcetera.). I'd try a tin and find out how your Grizzly likes them https://super17712111.losblogos.com/35033937/the-fact-about-super177-that-no-one-is-suggesting