I get the impression that different servers run different damage calculations. I havent done any scientific tests but every time I try a build on EU3 or EU7, it seems to behave quite differently on EU1. It may be a placebo since you are under more stress when playing against people rather than just casually testing builds in peace but could it be that some servers didnt get "updated" properly or something, just like the CN server run differently ? Maybe somebody with video editing skills should test bow/crossbow reload/draw times frame by frame on EU1,3,7, etc. and evaluate if there differences per server. If there happen do be differences, one could assume those also affect damage calculation.
Regarding actual ranged damage, I dont get how some people come across these insane damage numbers. I played with a 18/21 6 PD 155 archer WPF and a MW longbow the last week. I quickly noticed that 6 PD is an absolute joke, at one point I shot a bot in DTV ( donkey crossbower I believe ) ! thirteen ! times and he was still not dead. Realizing that my bow alone wouldnt cut it and I would need to have a good melee weapon as my main source of damage, I played with a MW composite bow from there on. On countless occasions I shot people in the face and in the body another time and in the absolute most cases they wouldnt die. One time my arrow even bounced on a plate guy ... bounced with MW bodkins MW composite and 6 PD ... wow.
I ditched my archer from that point and played melee alt until I could respec into more PD. I just did, went for a 30 str 15 agi 10 PD 139 WPF pure archer with MW yew longbow. Even with that pure cannon build, I shit you not, a 1st wave peasant in DTV survives a shot with MW tatars. Not always but they are occasionally. I dont know whats going on but I think I am better off hitting my enemy with 5 PS, no melee WPF and a 0 slot weapon than actually shooting them. Sure though, headshots deal quite heavy damage, but since you are required to use high PD low WPF builds and hard hitting, low accuracy bows, those headshots are often more RNG than skill dependant. The hitdetection for ranged getting worse and worse every patch is not helping either.