I'll use the BN2 as an example as I don't know the others as well.
The figures you suggest for the BN2 are for its ferry range which would be for maximum fuel, minimum equipment and with nil wind. As you add passengers you eat into your ability to carry fuel, reducing your total range, adding variable and reserve fuel will further eat into that figure.
Actually looking at the BN2 it seems that it does list 190nm range though looking at the bags+pax graph gives you a figure closer to 300nm which sounds more correct?
Just using some rough figures as an example, BN has the BN2B listed at MZFW:1,857kg while the MTOW is 2,994kg
That leaves 1137kg for fuel and payload assuming MTOW is possible. The AWS BN2 has 760kg of payload leaving 377kg for fuel, oil, hydraulic fluid etc
However Britten Norman gives a useable fuel load of just 492Litres without tip tanks. So @160lph gives you roughly three hours flight time, minus fixed and variable reserve so lets just say two hours of flight time which does get pretty close to 290nm.
So with a TAS of 145kts, 190nm definitely seems off. (Bare in mind the figures above are rough as guts)
BTW seems the AWS figures for fuel consumption of the 2B model and earlier are 30kgs more then what they should be, 170kg is the fuel consumption of the turbine model, the earlier Lycoming O-540 models normally consumed anywhere between 120-140lph which further suggests 300nm is correct.
Can anyone clarify the above? Seems Vostok might be right that some of the figures are slightly off (Just using the BN2)
Vostok I can't say anything for the others but the same idea will apply to other aircraft you've mentioned, most sources will only provide best range/ferry range as your range on the day will depend on payload / fuel / conditions etc.