I've wondered the same thing. I own both guns and have used the 10.5gr in the Quest 1000. I did break the spring, but then I have broken the spring in all of my guns, at least once, until I tuned them and lubed them properly. The Crosman Quest 800 calls for spring part # B19-00-4A for the .177 and #B18-00-4D for the .22 version. The B18-00-4D is the same spring used in the Quest 1000. I've replaced the spring in my Quest 800, .22, with the B19-00-4A (800 fps). It gives me a smoother shooting cycle and still plenty of power for rabbits out to 30 yards. Like another poster said, shoot what you want and order an extra spring and seal from Crosman, in case you need them. Spring is $5.70 and the seal is $3.60, plus $4 shipping. Happy Easter to everyone. Safe shooting.