I’ve been shooting 22” bolts and 100 grain heads. If I step down to 20” bolts will it pick up any FPS. What would be the down side. I have the room for shorter bolts.
Depends on the grain per inch of shaft. If they are the same weight and one is shorter and weighs less, yes you will pick up FPS.
But.. crossbows are usually loud and only 30yd weapons anyway. So picking up 5-10fps is helping anything but how loud the bow is.