I would certainly attempt them. There is certainly not reason that they might not work just fine in your Beeman. I've experienced fantastic 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://super17768900.blogsidea.com/42477389/not-known-factual-statements-about-super177