Hit, IndirectHit, IndirectHitRange and Armour, oops: Armor

[ACF]

Does anyone have a formula for the relationship between cfgAmmo's Hit, IndirectHit, IndirectHitRange variables and their effect on vehicles' armour that they could publish, please?

I've been tinkering with a low-tech realism tweak, initially to get rid of SABOT rounds for BMP1s and also resolve the 'sabot rounds go clang not bang' of the BIS config.  However, I don't want to pursue [my interpretation of] realism at the expense of the modded units being totally out of synch with existing units in terms of armour or firepower, so I need the formula to find a workable compromise.

[Dinger]

Hit = damage done if the shell comes into contact with the target.  This controls the "flash" part of the explosion
IndirectHit = damage done out to IndirectHitrange.
IHR = radius in which max IH is applied.  IH drops off dramatically outside of htis range (like in 1-2 meters in my experience).
IH and IHR control the size of the crater.

[Pathy]

you can change the hit sounds without changing power cant you?

hitGround[]={"soundHit",1};
hitMan[]={"soundHit",1};
hitArmor[]={"soundHit",1};
hitBuilding[]={"soundHit",1};

[ACF]

Well, I'd upped the volume on the ArmorHits, but then it got confusing - I must be doing something wrong somewhere:

I've tweaked an Abrams to have armor=500 and unity modifiers all the way round.  I've created some standardised ammo, basically rounds with:

H / IH / IHR
100/0/1
0/100/1
100/100/1

I naively expected that 5 direct hits of 100 would kill the target and 5 indirecthits something like.  Instead it took me:

H / IH / IHR - Rds to Kill
100/0/1 - 50
0/100/1 - 30-ish
100/100/1 - 30-ish

I've done a few tests with different IHR, but the bottom line so far is that damage is a tenth of the Hit value. Damage increases dramatically as IHR increases but hits a limit at about 5m (half the length of an Abrams (I'm firing at it's side)??). However, there's no obvious radius or area relationship to the IH effect that I can see at the moment.
I also haven't found anywhere where I've lost or gained an order of magnitude in armour or damage so I'm at a bit of a loss.
I can only assume at present that BIS use Hit just for a mainly cosmetic flash and most damage is done by IH and IHR.  Just to be clear, I'm trying to get sabot to do most damage with Hit with minimal indirect effects.  Any thoughts?