Make sure he has the barrel wrench and the feeler guage for it. If not, then deduct about $30.00 from the $300.00.
I had a Dan Wesson .22LR and my brother in law had one in .357Mag.
Fantastic guns. Strong and accurate as all get out. The big bore Dans "made their bones" in the silhouette shooters world, using heavy loads that would tear up anything short of a T/C contender.
Some would argue that the strength of the big Dans exceeds even the Ruger Redhawk, and is right up there with the Super Redhawk. I really wouldnt want to have to put money on it,,,,it's too close to call. If I REALLY was pushed into it,,, I think the Dan would still be shooting while the cast frame Ruger went to pieces,,,just MHO though.
For some reason though, the Dan Wesson never caught on except for a kind of niche gun. Pity. They really are top shelf guns.
$300.00 is about an average asking price for any Dan Wesson regardless of caliber with only 1 barrel/1 barrel shroud.
Dan Wesson has a website where you can get more info.
http://www.danwessonfirearms.com/