I might surely check out them. There's not explanation that they'd not do the job just good with your Beeman. I've had good luck with RWS pellets in all of my airguns (Hatsan, Crossman, Benjamin and so on.). I would attempt a tin and see how your Grizzly likes them https://super17733332.elbloglibre.com/35993217/super177-no-further-a-mystery