Hard to tell with my current survivor, who already has rifles in 16 and marksmanship in 18 prior to the change. Using a Barrett rifle.
Tested it out by spawning 9 hulks from 25 tiles away, then 50, then 60.
25 it seems normal. Hulks dead before they could even try to hit my survivor. Further distances is the same, but missing shots happen, or only 10 damage happens, but generally shots do 60-120 damage at 50+ range, unlike 30 or less where 200 damage happens, likelier to happen as the hulks close in.
For some reason though, turrets are super evasive. Took like 20 misses at 60 tiles away before a bullet hit.
Oddly, removing my survivor’s skills didn’t seem to change things much. Tested it on one hulk with 0 marksmanship and rifle. Damage seems to be the same, and the only noticeable change was doing precise aim took longer.