Sorry to resurrect this topic, but I think there is an important error in the description.
It says that a shotgun spread of 50 should result in roughly 50% of the pellets hitting the target. I did some testing to see if that is true, and it seems the scaling is not linear but quadratic. So it's not "pellets*0,5" but rather "pellets*(0,5^2)"
What I did: shoot a double barrel shotgun from piretez mod with buckshot at a target 15 tiles away. That thing has a spread of 48,75% and 10 pellets.
According to the description for his mod, this should result in roughly 5 pellets hitting your target on average. What I actually saw was an average of 2.1, which is significantly less than 5 but quite close to 2.37 that you would expect if the quadratic scaling was true.
I did some further testing with the military shotgun and buckshot. That thing has a spread of 75 and 7 pellets. Linear scaling will give you 5.25 pellets on average, quadratic scaling 3.9. What I saw was exactly 3.9 pellets hitting on average. This weapon I also tested at 20 tiles and got roughly the same number.
The quadratic scaling makes sense since you fire in a cone and the spread is in 2D and not 1D.
Now what really bugs me: Is this quadratic scaling also true for non shotgun weapons, or is that just ohartenstein23's code? Like, a 50% shot will actually only hit 25% of the time.
That seems congruent with my gut feeling. When playing I try to avoid 50% shots if I can because those always miss anyway. 75% and up is an accuracy where I feel comfortable that it is worth taking the shot...