[spoiler]
I'm afraid, that's not how this works: Soak is not reduced by more attacks.
But Waywalkers shot almost had a chance to do damage: 17 DV AP-2 vs. 20 Armor -2 is missing one point for more damage.
I repeat: You need to use Called Shot: Vitals Shot. This reduces your dice by 4 but you gain +2 DV
Alternatively: explosive ammo or APDS could help you. So it's 19DV AP-2 vs. 20 Armor
So:
Soak:
18d6t5 4 [18d6t5=4, 3, 4, 1, 5, 2, 3, 1, 1, 2, 6, 2, 3, 4, 4, 2, 5, 6]
15 DV vs. 14 soak boxes.
RIP
[/spoiler]
The hail of bullets that came down on the golem did nothing but produce ricochets - until Waywalker centered his shots directly at the base of the thing's neck. The head broke off and the thing tumbled to the ground, an iron girder still sticking out.