Hi AGN. I've searched but did not find the answer to my satisfaction. I'm planning to purchase a PCP in .177. (Not a FX) Would like to know where the workable velocities should fall.
1050 is a pretty sweet spot .. its fast enough to pack a pretty devastating whallop at general pesting ranges under 30 and flies flat so point blank aiming extends to almost 50y .. but like anything else, ultimate target accuracy is usually at a reduced anemic speed ..
Give or take from 500 fps to @ 925 fps is generally where most find best accuracy & best BC rating. Some pellets can be pushed faster with good success, but that is NOT typical and thus not a realistic anwser to your inquire
My Avenger shoots FX 25.4 grain pellets accurately at up to 35 yards at 930 fps muzzle velocity. But I'm not sure it does well at longer range. It has not the few times I've tried it. My other guns are set up to shoot at 800-900 fps. I think that is the generally suggested speed range. I have seen reports that well under 900 shoots better in windy conditions. I think it was in Hard Air I saw a piece that said 900 fps is the best velocity for slugs to minimize wind drift. That was lower than some people seem to want to push them.
Each gun is going to be different, and the weight of the pellet is also going to be a significant factor, not to mention the brand, style and a dozen other factors. Given that you are asking about 177 and assuming that you are looking to start with a medium weight pellet (8-10.5 gn) you could probably start with a velocity of 850-900 FPS and then go from there.