Light Machine Gun slows me down when I use it. I'm not sure whether it needs to for the crossbow, the reload is longer than the other rifles and the projectile is slower.
Magnum: 40 damage, 80 headshot, 6 shots, inaccurate if moving
Scoped Magnum: 35 damage, 105 headshot, 4 shots, even more inaccurate if moving
Crossbow: 100 damage, 1 shot, pierces players (only useful for zombies), always accurate
... when the other two are supposed to be side-arms...