I'd absolutely test them. You can find not rationale that they might not do the job just fantastic within your Beeman. I have had good luck with RWS pellets in all of my airguns (Hatsan, Crossman, Benjamin etc.). I'd personally check out a tin and see how your Grizzly likes https://super17768889.dailyhitblog.com/41409882/super177-for-dummies