Uncertain of the term "open the barrel". Single action revolvers such as the Ruger Bearcat are loaded one chamber at a time from the rear of the cylinder. The barrel is generally not a removable part, and is factory fitted in place.
If we have totally misunderstood your question (possible) please repost, or leave a message on my message board, and we'll try to help.
Ruger has sn information on their web site.
Ruger's website lists the current offerings.
You need to contact Ruger. You may have a prototype
200 USD
50-200
350.00
Ruger. 20-250 USD depending on specifics
50-500 usd
100-300 depending on specifics
You need a gunsmith.
Which model? Value varies with make, model, and condition.
22 Magnum Rim Fire