I'd undoubtedly test them. There may be not cause that they'd not function just good within your Beeman. I have experienced good luck with RWS pellets in all of my airguns (Hatsan, Crossman, Benjamin and so forth.). I would check out a tin and see how your Grizzly likes them https://super17798887.blogdun.com/36695820/not-known-factual-statements-about-super177