Line thickness in ps.map

[N R A]

Is there anyway to get the line thickness reduced when using the 'ps.map' 
command?

I've set the width to 1, but on our Laserjet IV the lines must be > 1mm 
thick. The text is fine though, even down to 4 point, so the printer and 
Postscript can cope, just that 'ps.map' seems to set lines very thick.

Is this something to do with the screen vs. printer resolution ?

Steve Culshaw
NRA North West
e-mail : nra at cix.compulink.co.uk (general usage)
or         sculshaw at cix.compulink.co.uk (Private - only checked at best 
weekly)