Here is the full list of all 47 Gun Bombers achievements.
Get 50 kills with pistol
Get 50 kills with revolver
Get 150 kills with Shotgun
Get 150 kills with Sawed-Off
Get 150 kills with Uzi
Get 75 kills with Sniper Rifle
Get 75 kills with Grenade Launcher
Get 75 kills with Bazooka
Get 75 kills with Minigun
Get 50 kills with Grenades
Get 50 kills with Molotov Cocktails
Get 50 kills with Flamethrower
Get all Hooligan achievements
Get 5 kills and survive the round
Survive round without doing any damage
Survive round without taking any damage and at least 1 kill
Get your first kill
Find treasure chest
Get one kill with Jackhammer
Get one kill with Chainsaw
Collect 1,000,000 worth of treasures
Dig 10,000 block of dirt/stone using Pickaxe or Jackhammer
Survive two land mines in one round
Steal someone's bomb
Get 3 kills with single Nuke
Get 5 kills with Rocks
Get 5 kills with Ducks
Survive round without bombs and atleast one kill
Survive round without guns and atleast one kill
Get two kills with one bomb
Get one kill with Napalm
Taze your bro
Disable bomb with Urethane just before it explodes
Escape Fire with Teleport
Inflict damage to two enemy with single Grasshopper
Complete Tutorial
Survive 10 minutes in Endless
Win a game
Get 5 kills with Moles
Get one kill with Turret
Inflict damage with Clone
Get one kill with Plastic Explosives
Kill player with bounty
Find the super diamond
Make a goal in soccer
Make 3 goals in one soccer match
Win a soccer match