But they would be with my suggestion.
No. Tying shotguns to critical builds only and even then with some randomized damage what could be achieved more easily, yet simple damage output increase is far from enough to ensure viability.
Better DR modifier for ammunition against armored targets, that is done simply by increasing the amount of DR the ammunition negates, knock-back effect working on full range with twice less efficiency or picture perfect based on distance keeping the 6 hex rule or and after the distance of the 6 hex rule in ideal version it would convert to knockdown not knock-back. Knockdown because it allows other sources of offense to lock on the target more easily, making it a more effective weapon as knock-back in most cases also will disallow further damage output due to the low range of the shotgun.
That might not be enough, shotguns might need few hexes of love concerning range, literally few.
Then maybe and ONLY maybe in specific locations and maps where close range combat is common, specialized builds could be utilized with a high tier shotgun in hands.
If it all fails you attach this one.
On top of that each knock-back could deplete the opponent of, for example, 1-2 action point/s
That's after 1 burst not ...
1 ap loss to target per bullet
I hope you don't mean it for bullet in each burst, 5 AP burst hitting 6 bullets decreasing 6 AP ...
Look, shotguns need to be viable not retarded imbalanced.
