Looking at the videos posted, it seems that these are all pretty short range shots. The demo with the pistol looked to be definitely inside 15m. The focus also appears to be less on increasing damage and more on making sure that you hit SOMETHING. At those ranges, especially with the shotgun, they already have something that fills that role: shot rounds. Flechette ammo or shotgun shells filled with shot are designed to spread out and make sure that you hit SOMETHING at least. Because of this, they tend to lose penetrating power. You'll notice that all those shots are done with paper targets, not with anything resembling a real target. It would be better to see a test using ballistics gel or even a pig carcass to determine the actual efficiency of the round. ANYTHING tears paper targets, afterall. There's a big difference between that, and getting through armor, or even a leather jacket.
With monowire, I'd say something like: -3 DV, -1 AP, +2 dice to hit, can only be used in Heavy Pistols and Shotguns. Heavy Pistols use Light Pistol ranges, Shotguns use Flechette ranges. Additional -2 penalty for ranges longer than short. (I.E., -3 for Medium, -5 for Long, -8 for extreme).