Spinny and Enoki are both directionally correct. There are also administrative implications to consider.
It really needs to be a gun that puts 'things' downrange, and let the 'things' do more work than simply transferring kinetic energy gained at the expense of lots of noise and recoil.
- Portable energy weapons are illegal at LL-2.
- A magazine-fed shotgun might be thought of by LBB standards as a light assault weapon, and illegal at LL-4.
- Personal concealable weapons are illegal at LL-5.
[side Q: does sophont body habitus affect what's considered "concealable"?]
- But a shotgun is legal to LL-7.
And I'm wondering if a break-open double-barrel pistol-grip shotgun, loaded with two low-velocity less-lethal rounds (gas, tranq, sandbags, taser darts) might even qualify as a "stunner" and get as far as LL-8, but that's very very unlikely.
So. Short shotgun with aspirations of launching small grenades; tube-fed, magazine-fed, or even break-open double barrel; with a clip-on laser tube and matching power pack for when you really need to say "FU" at lightspeed. You could add a side-saddle shell holder or a bandolier for when the situation fails to accommodate your plans and you need options to make your message a little more specific and to-the-point.