When I was growing up, we had a Benjamin [Franklin] pneumatic pump air rifle. Air pressure stored was dependent upon the number of pump strokes used.
All spring-piston air rifles I have read about - admittedly I do not keep up with spring-piston air rifle technology - use a single stroke to cock its piston. Are there, or have there been, spring-piston air rifles that incorporate the ability to use multiple strokes to increase piston's release pressure. This has always appeared to be a moderate cost method to significantly enhance velocity-power of this technology.