Honestly [Critical Delay] is unnecessary, but it just saves on a forma. Same with using [Infected Clip].
[Speed Trigger] is a must to compensate, otherwise I would use [Hammer Shot] for yet more Crit Damage and some more status.
Maybe it could even provide enough status to go for [Primed Cryo Rounds]
+1 forma to fit the exilus, but only if you want [Terminal Velocity], and not ammo mutation