I had two separate character ideas, one was the elite sniper "One Shot One Kill, at any range", and the other, a brute Troll with the highest Armor and BOD I could make. When I started thinking about the viability of these characters, I tried pitting them against each other and wanted some help.

So here I am, asking you guys to help refine my characters. My troll tank shouldn't be fully maxed out in terms of BOD, so I know there's a bit of leeway there.
SNIPER
13 AGI - Exceptional Attribute, Restricted Gear x3, Genetic Optimization, Muscle Toner x4, Suprathyroid Gland
6(8 ) Longarm(Sniper)
Barrett Model 121(18F Restricted) - 9P, -4 AP
Dice Pool: 13(AGI) + 8(Skill) + 2(Smartgun) + 2(Take Aim x2 + Image Magnification) = 25
TANK
12 BOD - Genetic Optimization + Suprathyroid Gland
Didn't get Exceptional Attribute because Genetic Heritage(Optimization) + Restricted Gear x2(Pain Editor, Suprathyroid)
Physical Track = 14
16 Ballistics Armor - 6(Form Fitting Full-Body) + 2(Full Secure-Tech Set) + 7(Vashon Island: Steampunk Set) + 1(Troll)
So I presume the best called shot would be to negate armor, Sniper Rifles have AP -4, so 25 - 12 = 13 Dice, 14 if EX-Explosive Ammo.
With no defense (Tank is unaware of attack), the attack if we buy hits is 3 net hits. If roll average 5 hits?
So with Barrett DV = 9, so total 12/14 DV. Add onto that EX-Explosive Ammo is +1 DV for a total of 13/15.
So with the Troll buying hits with Damage Resistance (minus 3 DV), the Sniper loses because it's not a One Shot Kill, and depending on the other stuff I could put on the Troll (like Trauma Dampener and/or Platelet Factories) further reduces the ability for the sniper to "Head Shot" him.
Is there anything else the Sniper could do (other than Edge/Luck) to boost up damage?