Guns are modular: attachments and what they change
A gun is the bare gun plus the parts you snap on. Here is what a silencer, an auto switch and a printed grip each do to the 9mm sidearm, with the game's own numbers.

Every gun in the game starts as the bare gun. Parts are separate items that snap onto its sockets, and some of them you print yourself. In the game
The rule underneath all of it: a part changes the gun, never the bullet. A 9mm round does 7 damage whether the gun is bare or loaded with parts. What changes is how often it fires, how hard it kicks, how far the shots wander and how loud it is.
The three parts on the sidearm
Silencer. Noise drops to 35 percent of a bare gun, or 20 percent with subsonic ammo. It takes 5 percent off the kick and adds 5 percent to the sway.
Auto switch. Fits the 9mm sidearm only. It turns one shot per pull into full auto: 0.05 seconds between shots instead of 0.22. The price is control. Spread goes from 0.014 to 0.09 and the kick climbs to 1.7 before the silencer trims it.
Printed grip. A sleeve you print in flexible plastic and slide over the handle. It takes 18 percent off the kick, 9 percent off the spread and 24 percent off the sway. A worn grip does a little less.
Why bother
Because the same gun can be a quiet tool or a loud, messy one, and you choose which. A silenced sidearm is for not being heard. The switch is for a bad day. The grip is what makes the switch usable.
What else snaps on
Rifles, submachine guns and shotguns take a red-dot sight (1.25 times zoom). Rifles also take a 4 times scope. Neither one changes the round either. In the game

