There's a fragile balance for accuracy, speed, numbers of shoots per fill and how long your c3 bumper will last. It seems to me. The lower you can keep regulator setting, but tunning for the highest speed. My C3 bumper seems to last the longest. Obviously the lower you can keep your regulator setting, the higher shoot count. This is where JSB is going to love you. You'll need to try many different settting to find the one that works for you. As other people have said 860fps-920fps. Id recommend 860fps as a great place to start. I've noticed that many .30's like the the 868-875fps range with the 44.75gr JSB pellets. Please remember this only a guide and not a rule. You'll need to find what works best for you. Good luck