Here is the full list of all 48 Necromunda: Hired Gun achievements.
Kill a Genestealer with a grenade launcher
Kill an enemy with every weapon
Trigger all mines on Steel way
Fill one faction bar
Finish Kaerus without using any other weapons than the Ironfist
Finish Avarus without using the grapnel
Finish a mission using only special weapons
Place the 5 bombs in a gap of less than 3 minutes in Escher Lab
Let Brickjaw live in Koloss 44
Kill 5 enemies in one use of Strength Booster
Open 20 chests
Finish the Main Campaign
Finish Chapter 12
Finish Chapter 11
Kill 100 enemies while wallrunning
Kill 60 enemies with the Perfect Aim module
Finish Chapter 10
Finish Chapter 9
Kill 30 enemies with the Crush module
Kill 100 enemies by using Augmetics powers
Take out 50 shields with the grapnel
Kill 30 enemies with the Blast module
Wallrun 2500m
Upgrade one implant to the class 4
Finish Chapter 8
Finish Chapter 7
Travel 5km using the grapnel
Buy an upgrade for your Mastiff
Finish Chapter 6
Customize every aspect of a single weapon
Finish Chapter 5
Amass 100.000 credits
You have performed 100 Takedowns
Finish Chapter 4
Kill 10 enemies in a row with headshots only
Finish Chapter 3
You have killed 100 enemies with a headshot
Finish your first secondary mission
Finish Chapter 2
Kill 30 enemies with your Mastiff
Kill Brickjaw in Koloss 44
Complete the shooting training in Martyr's End
Pet your dog in Martyr's end
Buy your first upgrade to the Rogue Doc
Finish Chapter 1
Finish a mission with an S rank
Finish all main missions with a rank of A or more
Find a +3 weapon