No. Shotguns do not need to have their bullets disapear at a certain range. That is less than optimal.

They simply need to be shot with a wide spread, a large amount of bullets (I do not know if this is a big deal with lag.( I am thinking 5 minimum, but I would like to see 7-15 small pellets shot) and low damage. Damage drop-off really is not necessary. The fact that the pellets will spread and they already deal individual low damage will mean that they the farther away the enemy is the harder it will be to deal significant damage.

However, up close when many pellets hit, it can deal a lot of damage. If all pellets can hit, it should be close to I say 36-40 damage. If there was 12 pellets per shot, each pellet should deal 3 damage.

Actually as of now I am just describing how shotguns should be modeled in general. The way shotguns could vary from each other is
1: Number of pellets.
2: Damage per pellet.
3: Spread (some should spread more than others- spread is a benefit and a curse)
4: Freeze (More damage and pellet #= Longer freeze)
5: Reload and magazine size.

Id say the DBS should have 8 pellets per shot, 3-4 damage per pellet. Close to moderate spread, long freeze, fast reload, and of course the 2 magazine size.