Don't ask that from airsofters. The ones who took time and energy to actually measure it, will feel ashamed when they read that others' guns can reliably hit a man sized target at 100 meters.
I have seen videos that stated "100 meter shot" and calculating from the BB's flight time it was only 30 - and then when I commented it on the vid, the poster said: yeah, it might have been 30. I have heard numerous claims reaching 80-100 meters and when I asked for proof they all said: ok, I will take a vid. They never returned. People usually eyeball distances and don't count the few (dozen) flyers.
A fine tuned AEG shooting 350fps (with 0.20g) can hit a man quite reliably at 60m and headshot nearly every time on 40m with heavy BBs.
HPA or similar kits might reach further because of the joule creep, ergo higher energy with the heavy BB used. GBBRs can have joule creep too but they are usually way less accurate than an AEG.
50m is the range for a normal, well maintained AEG, with average 0.25.
40m or less for non-maintained AEGs and/or using 0.20.
Something like that.