Alan,
Ruger has great customer service, but they won't sell you a barrel, hammer, trigger, hand, pawl or cylinder, as they say these have to be factory fitted!
Also, what they are telling you about the 4 5/8" barrel for your Bisley is that the barrel is not a standard factory offering, therefore it would constitute a custom gunsmithing service which their policy forbids... (don't ask me why). In summary, if it doesn't come as a factory option, they won't install it at their factory service center!
However, barrels are available in all lengths and configurations from Brownells, Gunparts and Jack First for about ำ.00 if my memory serves me correctly.
Brownell's Inc. <a href="www.brownells.com" target='_blank'>www.brownells.com</a>
Jack First Gun Parts <a href="www.1stingunparts.com" target='_blank'>www.1stingunparts.com</a>
Gun Parts Corp. <a href="www.gunpartscorp.com" target='_blank'>www.gunpartscorp.com</a>
Also consider a take off barrel from one of the custom smiths.... they are often times brand new and very reasonable! Some as low as 20 bucks and with front sight!
David Clements <a href="www.clementscustomguns.com" target='_blank'>www.clementscustomguns.com</a>
Gary Reeder <a href="www.reedercutombuns.com" target='_blank'>www.reedercutombuns.com</a>
John Linebaugh <a href="www.sixgunner.com/linebaugh/default.htm" target='_blank'>www.sixgunner.com/linebaugh/default.htm</a>
Hamilton Bowen <a href="www.bowenclassicarms.com" target='_blank'>www.bowenclassicarms.com</a>
These should give you a place to start, and not worry about Ruger's protocall on non-standard modifications!
You'll like a 4 5/8" Bisley!
God Bless,
Marshall