Trying to understand in-game DAM rating

[DanielCoffey]

I am looking at a couple of the DAM values in-game of some weapons which seem a little overpowered and I am trying to understand the factors which contribute to that DAM rating.

 

Example 1 : Combat Shotgun DAM 55

Example 2 : VEPR-12 Molot Drum - DAM 681

 

Both are 12-gauge.

 

Is it something to do with the fire rate? In xEDIT, the combat shotgun has damage 72, projectiles 12, fire rate 1, clip 12 and the VEPR-12 has damage 25, projectiles 8, fire rate 10, clip 30 and supports full auto.

 

Both the weapons above are somewhat low in condition if that makes a large difference.