- as regards battle sense seconds, in et source code it says 45000 milliseconds (45 sec) if jaymod changed that I can't say, don't think so, but it should be easily checked if you want I'll check, but I think we can safely assume they left it as it was.

- for damage: yes there is damage falloff, but you cannot calculate the distance of the hits, remember it's like /weaponstats. Damage falloff starts from 1500 units (a medium/close range fight is about 300units). I think we can assume that damage is full in most fights.

- Helmet reduces damage by 20% (80% of original damage, so from 50hp to 40) but again we don't know from weaponstats, let's assume helmet is off, to please headshot lovers and make it easier :p

Talking about battle sense, in my opinion that bonus should be at most equal to half a kill, otherwise it's not just a bonus, waiting cannot count more than fragging an enemy

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to summarize:
1. calculate damage from hits and hs
I don't wanna write a novel to say my reasons, since my posts are already so long but considered that rifle is rarely used, and sten is harder to use than mp40 due to overheating, so its lower damage would penalize it, we don't really need a weapon table, but using a 'standard' 18hp for bodyshot and 50 for hs would be realistic enough, and easy to implement. Or make a table if we want to be more precise.
damage = (hits-hs)*18 + hs*50

now we have:
damage, kills, xp (engi, revive, heavy weapons, battle sense)

the point is now, how to balance?
some real data would be useful here, like some good rater kindly doing /weaponstats before and at the end of a good match, I ain't no superstar so I cannot use my stats, low+ max or Giriel can take them from the database I don't know

Let's estimate how much points per minute you generally get from these things, and balance them according to the skill actually needed to achieve them. Atm up to 10 ppm for battle sense is way too high. Surviving takes skill only if you are fighting, not if you play more defensively to get the points for battle sense after a fight.