I think this hero is kinda bad in that the hero feels like just his shotgun and sniper and thats it.
The shotgun damage is bloated to the point it basically puts someone to quarter HP because its all he has in a fight. sprint and land mines that are overal pretty damn mid skills without some other type of combo.
make him kinda whack as a hero when all his damage is front loaded onto a single skill.
I suggest reworking the hero so his kits damage is more spread out and more interesting to utilize.
example you dont have to take these but ideas.
Passive :
murdock gain his movespeed only when targets HP were low the sirens trigger and he would run them down.
Shotgun: damage significantly reduced but does a similar armor shred function.
Land mines make them invisible after being placed and make them slow when you step on them.
New skill could be a number of things hes a cop right be creative make him truley a space cop with the rework.
that is all.