Gunny above has about a 1.7% spread (16 fps spread/915 fps avg). I suspect much of that variation is from the pellets, orientation of the barrel firing through the chrony, the breeze, and alignment of the stars and sun. It's extraordinary, especially for .25 cal. Best way to shrink it is to limit shooting to fewer shots, like stop at 42. Would've shrunk the spread to 10, or about 1%. Probably could pick a smaller string and done even better.