- Assuming you start with a package of 16-20 ammo-bits, if you roll a 3 or 13 on the d20 to hit, you are down to 3 ammo-bits in that package until you can buy more ammo.
- You can't run out if you roll a 3 or 13 in the first three shots of your first encounter after stocking ammo.
- This assumes you're not retrieving missiles ... I guess it's not too much complication to say you run down only on a 3 if you retrieved missiles after the last battle, otherwise you run down on both numbers.
Together with some ideas for special missile weapon fumbles, I reckon this might justify one page in the Next 52. What do you think?