Woohoo, dead doggy

Wow, they've sent a really tough cookie into this fight. But yeah, all those mods should stack (and he gets more boxes on his damage monitor), but I count 12+2+3-7=10 dice from inherent armor +18 Fullbody Armor +6 Body =34 dice. So he loses the last succcess and gets one damage more

(I'm just glad it's not a milspec with hardened armor)
But first things first: Arthur sits in the car, so the rules from p.205 core apply:
Sitting: -2 defense, but good cover gives +4, so 12 dice total (5 Pilot + 5 Maneuver) -2 for short burst
Arthur Defense:
10d6t5 3 [10d6t5=1, 3, 3, 2, 6, 3, 5, 3, 5, 3]
DV 16 AP-6 vs. BOD 4 + Armor 20 + Car Armor 6 - AP6=
Arthur Soak:
24d6t5 12 [24d6t5=2, 6, 4, 6, 3, 6, 5, 6, 6, 6, 2, 6, 5, 4, 4, 4, 3, 2, 2, 4, 3, 5, 5, 5]
Modified DV 4 S
And now comes the funny part: Vehicles and drones don't take Stun by RAW...
But you could rule that it instead has a stun track of 0 and Stun damage is therefore calculated as half Physical (so DV 2 P)
Isaint resist:
Soak:
24d6t5 6 [24d6t5=2, 1, 2, 6, 2, 5, 4, 6, 3, 1, 3, 2, 5, 6, 1, 2, 2, 3, 2, 3, 1, 2, 2, 6]
Isaint takes 6 Stun damage, but doesn't go prone(Physical Limit 9)Ini for Round 2
Ini:
14+4d6 34 [4d6=6, 2, 6, 6]
Wow, looks like pain is a motivator for Isaint. I'll activate Adrenalin Boost for an additional +2 to Ini and a total of 36 Ini
Arthur Ini:
14+4d6 30 [4d6=6, 2, 6, 2]
Isaint Ini 36:
Simple action: Command Arthur to shoot at Handler
Simple action: (You've been waiting for it, haven't you?) 3 round Bullseye Burst! vs. Rifleman
Free action: Adept Centering
Free action: Called Shot
AGI 7 + Skill 8 + Smartlink 1 - Wounds 2 - Called Shot/Adept centering 0
Bullseye Burst:
14d6t5 4 [14d6t5=5, 3, 4, 2, 3, 1, 6, 5, 3, 3, 4, 3, 6, 2]
DV 12 AP -13 Defense -4 (-2 Defender Prone -2 Wounds)
Move around corner to break line of sight to VAN 1Arthur:
Aim: at Handler
Shoot FA Burst:
Arthur Shoot:
12d6t5 2 [12d6t5=6, 4, 2, 3, 3, 3, 6, 2, 4, 4, 4, 2]
DV 15 AP +4 Defense -6
And I add my voice to adamu's:
We are having a fight against 5 soldiers, 2 Barghests, 1 Hacker, 1 Decker, 1 Mage and a butt load of drones with 6 Runners, 1 Hound and 1 Drone on the other side.
And we only started last week with the fight. If anything, we are doing extremely well (and more important learn quite a lot about the rules while we do it. Always remember, I may be rules lawyering here a bit much while trying to keep my and the other characters alive, but I'll always abide by your decision

)
But if you want to speed this up even more, you could have the Players roll the defense tests for their opponents as well.