The gun runners are in the game. They're known for packing some firepower.
Yeah but I mean stuff like Tesla Cannon and Auto-Axe only exist on the east coast because they're new designs.
How wound the Gun Runners get them?
For what reason did they go to east coast?
Stuff like that.
If it's in the vanilla game it's going to be considered canon and they need some way to explain the stuff being there. (Heavy Incinerator for example is in New Vegas. How did it get there? Who created it?)
This DLC would be completely non-canon and only for flavor really.