So I took the time to measure out the impact sizes of 3 different guns.
Browning Hi Power - 9mm
M1 Thompson - 45acp (11.5mm)
Winchester M1912 - 12 Gauge #0 Buckshot (13pellet)
The graphics of the impacts seem to be consistent at 2 pixels per millimeter of of size. 9mm shows 18 pixels for the hole, 45 (11.5mm) shows 24 pixels. However, the shotgun shows 2 pixels, indicating a 1mm projectile which is effectively birdshot.
#0 Buckshot holds 12 pellets on average and should be the closest to what is indicated in game. #0 buckshot is 8.13mm per pellet and should show an impact size of 16-17 pixels.
I will calculate the shotgun energy/damage per pellet in a moment. But roughly should be about 20-25% less energy per pellet than a 9mm in game.
The velocity of the shotgun in game is almost half what it should be, showing 200m/s but should be closer to 365m/s
Energy
#0 Buckshot at 8.13mm at 48gr per pellet at 365m/s (1200fps) has about 208J (154ft lbs) of energy. Multiplied by 12 = 2496J or 1848ft lbs per shot (+208J for that 13th pellet in game for a total of 2704J or 2002ft lbs.
The spaded Winchester M1912 shows 44.6 damage, /13= 3.43 damage per pellet. Convert that to J and we have 1 damage point per 60.6J of energy.
The Browning Hi Power 9mm has 5.5 damage, with a 124gr bullet at 370m/s has 549J (405ft lbs). Same formula, 1 damage point per 99.8J of energy.
The damage per joule of energy is wildly inconsistent. I can run these numbers across several different guns and they will all be different.
