Sincerely, I have to love the ammo rules as they are stated in the rulebook.
Obviously but over the surface, it's an abstract system but inside I think it's realistic. I will try to explain it better:
In other games, players have bullets, clips, magazines, etc. They are a countable resource for characters. But then, the problems come with some situations which are not only unrealistic but frustrating for the GM:
- When players know that there is a predictable danger situation, or better said, when a combat might be guessed near the horizon; I have to insist (insistently) to the players to keep track of which weapons and ammo their characters carry. If you say nothing or forget it, they will tend to carry all the ammo a character has on his/her sheet. If they have 1.000 bullets, they will carry to combat the 1.000 bullets on his/her character (I don't know where, but they do; I suppose they have very big coats). For me, it's really frustrating to remember some players this fact... with these ammo rules, you avoid that since a character could have 1, 2 reloads, no more.
- In combat, there are some players who "forget" to keep track of his/her ammo constantly. I think they are not cheating, I prefer to believe that they tend to forget in some way but in some cases I had to warn someone in this way: "Please, remove three bullets from the last burst", "I did it" he answered and lied, "No, you didn't, remove the three bullets. Ammo is not infinite". Even I had to pick up the sheet and erase the bullets for them... This is frustrating too.
And then in Alien, all change with the Ammo rules. You don't have to argue, you don't have to remind all time to erase bullets and keep count of them. You only have two reloads, and when you roll a 1 you remove one reload. Perfect!