Gamma World: The Wanderlost
House Rules for Ammunition
The official rules state that a character who fires a gun (or other weapon that requires ammunition) once in an encounter is considered to be conserving ammunition and will still have ammunition at the end of the encounter. If the character fires the weapon twice or more in an encounter, he is automatically out of ammunition when the encounter is over.
My house rule is that a character may fire a gun a number of times equal to his level in an encounter and still have ammunition afterward. For example, a 3rd level character who fires three times or less in an encounter will still have ammunition after the encounter.
If the character fires more than the above limit in an encounter, he must make an Ammo Check at the end of an encounter to determine if he still has ammunition. The Ammo Check works similar to an Omega Tech Check. The player rolls 1d20: a roll of 10 or better means he still has ammo; a roll of 9 or less means he is out of ammo.
If the player rolls a natural 1 on an attack roll (a critical failure) with a gun, he is automatically out of ammunition without the benefit of an Ammo Check.