I've sort of fixed the slingstone friendly fire issue by modifying the following lines for data/descr_projectiles.txt
Before replacing the stone, rock, cobble, and glandes configuration, make a backup of data/descr_projectiles.txt
Code:
projectile stone
;effect small_arrow_trail_set
end_man_effect man_impact_tiny_set
end_shatter_man_effect man_impact_tiny_set
damage 0
radius 0.1
mass 0.05
;accuracy_vs_units 0.06
accuracy_vs_units 0.09
affected_by_rain
;min_angle -60
min_angle -30
;max_angle 70
max_angle 50
velocity 13 39
display particle_trail
model data/models_missile/sling_stone.cas, max
projectile rock
;effect small_arrow_trail_set
end_man_effect man_impact_tiny_set
end_shatter_man_effect man_impact_tiny_set
damage 0
radius 0.035
mass 0.1
accuracy_vs_units 0.2
min_angle -30
max_angle 50
velocity 6.7 20.2
display particle_trail
model data/models_missile/sling_stone.cas, max
projectile cobble
;effect small_arrow_trail_set
end_man_effect man_impact_tiny_set
end_shatter_man_effect man_impact_tiny_set
damage 0
radius 0.05
mass 0.056
accuracy_vs_units 0.17
min_angle -30
max_angle 50
velocity 13.4 90
display particle_trail
model data/models_missile/sling_stone.cas, max
projectile stone
;effect small_arrow_trail_set
end_man_effect man_impact_tiny_set
end_shatter_man_effect man_impact_tiny_set
damage 0
radius 0.035
mass 0.1
accuracy_vs_units 0.15
min_angle -30
max_angle 50
velocity 13.4 90
display particle_trail
model data/models_missile/sling_stone.cas, max
projectile glandes
;effect small_arrow_trail_set
end_man_effect man_impact_tiny_set
end_shatter_man_effect man_impact_tiny_set
damage 0
radius 0.016
mass 0.02
accuracy_vs_units 0.12
min_angle -30
max_angle 50
velocity 13.4 90
display particle_trail
model data/models_missile/sling_stone.cas, max
Note that this configuration changes the min_angle and max_angle. Friendly fire for slingstones still exist however, but it's much less extreme than in vanilla 2.35a