Ok so im not willing to post too much on forum where it seems 70% of people can't spend an hour to play and then get killed by the patriarch at the end(or whatever,frickin arcade gamers)because it seems peoples are never happy with what they got...
but here I got the answer(finally) for this question:
Yes,the dual HandCannons works with the sharpshooter perk.
Here's the test I made:
WestLondon,on Beginner with Fleshpounders only.
-Sharpshooter perk
Dual HandCannons:9 shots in the head.
Single HandCannon:9 shots in the head.
(the number of bullets needed may slightly differ to one more or one less bullet...)
-Support Perk
Dual HandCannons:14 shots in the head.
Single HandCannons:14 shots in the head.
(the number of bullets needed may slightly differ to one more or one less bullet...)
I also tested this with the medic perk and came out with the same result(~14bullets)
and I tested this on 5 to 10 Fleshpounders for each.
And for the trick that make's the dualies count as shotgun damages for gaining experience in the support perk(and not countin 'em for sharpshooter...)I guess its just a bug that might be solved soon.