How to calculate damage against spirits?

Ok, so spirits have immunity and the modified damage value of a mundane weapon must exceed twice the force of the spirit in order to do any damage. Ok, that much I get, but how do we calculate armour reduction for hardened armour?

Do we….

A: Deduct armour modification from the spirits armour BEFORE calculating if the DV exceeds the (now modified) armour of the spirit

Example: Spirit (F5) is shot with a predator IV with ex-explosive rounds and reduce its armour by -3 so that it now has an armour of 7. Predator IV does 7P base damage and shooter gains 3 successes bumping the damage up to 10P –armour, making a total damage of 3P (Resisted by spirit with Body+Modified Armour)

B: Get enough successes in the above example to bump up the damage to 11P and THEN reduce armour by -3 making a total of 4P resisted by Body+Modified Armour?

You always apply mods first and compare then.

And no, Hardend Armor doe not substract DV, so the Spirit would resist 10P with reduced Armor and Body.

AP is deducted before calculation, but to my dismay auto and burst fire damage mods are added after calculation. This means it´s rather hard to discribe your toxic air spirit as a cloud of foul smog. Judging from what happens to it when you shoot it, it's more like an armored statue of a cloud of smog...

Naw, because the bullets go right through it.

It's a cloud of smog, not Superman.

What about called shot? Apply before or after?

if anything, those spirits are magical energys taken physical form.
therefor it may well be that when a bullet strike a area of air given "life" the air may harden (local area of high speed wind anyone?) that deflect or in any case makes the bullet bounce off.

hell, if one wants to be anal one can ask how anything can harm a gas or energy based spirit (air and fire), or maybe even a liquid one. i say its a matter of intent. but as its done with a ranged weapon, your not putting your whole "soul" behind it and therefor the spirit gets a easyer time to resist

in the end its metaphysics. i would think even in-game magicans debate why a gun can harm a cloud of gass. and if the spirits know, the are not talking. and i can understand them. why tell anyone how they can become more effective at hurting you?

and if you go down the route of bullet pass-thru, you risk getting into the mess of the bullets hitting stuff on the other side. bullets do not magicaly dissapear if they dont hit a target (this is why bringing a high powerd rifle to a downtown firefight may well be a bad idea if your a member of the police).

My problem is just with the rules contradicting the way I want to discribe the action. I´m not very anal over this kind of thing (my sig should give a clue about that). The reason I ask is because some who are more anal always point out the systematical flaws in my house-rule suggestions. That way I can make more informed adaptions of the rules in game later on.