I think the stats should reflect the mechanic. Something like the Loose Cannon with its Double Donk ability.
The launcher part should charge faster than a normal sticky bomb launcher and detonate on their own once making contact with a surface after several seconds.
However, to balance this, make the stickies do less damage than a normal sticky (-20%) and make the fire rate slower to discourage spamming.
And to encourage people to practice and get better with the airshot mechanic, include a rewarding stat for pulling it off such as a boost to the blast radius and/or mini-crit when shotting the stickie out of mid-air.

As for the stats of the rifle side of the gun, I'd say make it like the Sniper's SMG but with a much slower fire rate and more accurate at longer range with no reload.