Quote Originally Posted by Tevo77777 View Post
4. The world is full of hundreds of different pistols and they seem to have a purpose in real life, and are cool in movies/games, but they’re useless in D20 Modern.
The world also has hundreds of different cars, graphics cards, clothing manufacturers, and lots of other stuff.

Simulating things down to a high level of detail is a trap, unless that is all you want a game to do.

At some point, you should just say:
Handgun:
1d6 accuracy
1d10 damage
1d6 ammo

If you want to name the specific gun, have someone who knows a lot about guns do so.

Mechanics here are:
1) You add 1d6 to the attack roll.
2) It does 1d10 damage
3) When you attack, roll 1d6; on a 3+, your ammo die becomes 1d4. If you roll 3+ on 1d4, you run out of ammo.

You can choose to attack with care ("pick your shots"), giving you "disadvantage" on accuracy in exchange for advantage on ammo (roll accuracy twice, take worst result; roll ammo twice, take better result).

Semi-auto weapons permit you to use ammo liberally - advantage on accuracy, roll twice for ammo.

Burst-auto weapons let you do burst-fire - advantage on damage and accuracy, roll twice for ammo.

Full auto weapons let you empty a clip - double damage dice, roll 3x for ammo.

Yes, this means you aren't counting bullets. And sometimes you'll run out of ammo after hitting someone once.

In this model, "attacking with a gun" may involve shooting any number of times.