Been wanting one of those little stainless Ruger Bearcat Shopkeeper models for a while.
A few days ago a slightly used one crossed my path and I bought it for a good price.
Got it home and thoroughly cleaned it.
When I tried to insert cartridges into the chambers they wouldn't go in without forcing them! WTF?!?!?!
InterWebz research shows this to be an issue with this model.
Examining the cylinder shows what I believe to be the issue.
1.) The chambers are cut tight. Ruger should of cut these more generous on a .22.
and
2.) The lip of the chamber is peened from firing pin strikes. Enough so the damaged metal impedes the insertion of the cartridge. This also prevents the cartridge from seating as deep as possible which results in the cartridge case head hitting the recoil shield and binding up the cylinder when attempting to cock/rotate the cylinder.

 
I've already ordered the Menck tool from Brownell's to recut the chamber. I'm hoping this solves the issue without sending it back to Ruger.

The peened lip is likely the biggest issue with insertion of the cartridges.

The above may very well be the source of your problem. Also it sounds as if the previous owner may have done a lot of "dry firing" with that rimfire revolver,
something that is generally frowned upon. I suggest you also check the tip of the firing pin...Good luck....<><....:)

If there is an issues with the firing pin contacting the cylinder then you may want to return it to Ruger. The Bearcat is safe to dry fire as stated in the factory manual at the top of page 16.

https://ruger-docs.s3.amazonaws.com/_manuals/newBearcat.pdf

Received the Menck tool today. 2 minutes, few drops of oil, and some elbow grease solved the issue.
Tried several brands of ammo in the chamber. Remington, Aquila,CCI, Federal all drop right in now.
Winchester 333 will NOT. That ammo is crap anyway. After I shoot this batch up I will not ever buy that weak stuff again. It won't even cycle half the semi-auto's I have.

As usual its amazing what the right tool can do.

Range day tomorrow!