Attack dispersion measures how much missed shots miss by, with higher numbers meaning that missed shots go into a wider area. Hand Cannons have a very high attack dispersion (0.75) compared to arbalest (0.33). This is important because missed shots still deal (half their) damage if they hit another unit. Lower attack dispersion means missed shots are more likely to hit another unit. This is very important to Hand Cannons because they miss roughly 1 in 3 shots.
My suggested changes for Hand Cannons
Missed projectiles deal full damage
Attack dispersion from 0.75 (= conq, jani, organ gun) to 0.5 (Arbalest = 0.33)
Attack delay from 0.35 (= Arbalest) to 0.21 (= Chu Ko Nu)
Food cost from 45 to 35 (95 to 85 total resources)
Training time from 34 to 28 (Arbalest = 27; Skirm = 22)
Attack dispersion: 0.75 (current)
Attack dispersion: 0.5
Attack dispersion: 0.33 (same as arbalest)