Black powder in a Blackhawk

If you run a lot of blackpowder ammo, it probably would be a good idea to go inside and clean about once a year , but you should be doing that anyway.
Prober blackpowder loads you won't have much "residue" outside of the cylinder mouths, forcing cone and barrel.
Clean up is fairly simple, when you're done shooting for the day, take the cylinder out, blow about 4 deep breaths down the barrel, take a dry flannel patch on a jag down the barrel, followed by a couple of damp ones and another dry. If you're using a decent powder and bullet lube, the barrel should be clean. Repeat the process on the cylinder. Then take an oil soaked patch and push down the barrel and each one of the cylinder chambers, take that last oil soaked patch and wipe down the outside of the gun.
Don't forget to wash your brass.

If it were a typical cap and ball revolver, like a Remington, for example, then a complete tear down and cleaning isn't a big deal.
But with the increased complexities of the Ruger, that might not be such a good idea.
In additon to what Mr. McDowell said, swishing the gun around in a bath of mineral spirits might clean the internals plenty good enough, followed by a spray cleaner.

Take the grips off the frame.
Wipe out the inside & the outside with an oily paper towel.
Clean the barrel & ejector channel & ejector rod with soapy water & dry with patches & paper towels.
Now, spray some WD-40 into the trigger recess and the hand channel.
Cock the gun and spray down between the hammer & the frame.
Spray down the bore and into the ejector
Set the pistol against something for 1/2 hour or so to let it drain
Meanwhile, clean the cylinder in soapy water, dry & oil it.
Now wipe everything down with a paper towel.
Run an oily patch down the bore.
Put the grips back on & put it away.
Been doing it that way for 30 years, and not a speck of rust, inside or out.
--Dawg

I go about 60 to 80 rounds shot through my cap and ball revolvers between complete teardowns. For a cartridge revolver like a Blackhawk you can easily get by with up around 150 to 200 rounds before I would bother with any internal action cleaning.

To avoid getting the water I use for the barrels on my Remingtons I use an old gallon size bucket and fill it so the forcing cone is barely on the surface. That keeps the water out of the action if I'm not planning on an internal cleaning. From there some brushing and patching and I'm ready to dry and lightly oil the bore along with the exterior.

Another hint. I've yet to encounter leading in my C&B wheelguns so I long ago picked up a nylon bristle bore brush which I use instead of the brass wire brushes. It does a great job of scrubbing away the fouling without being at all aggressive to the metal when it's not needed.

Looking at this Ruger tech video on stripping the Blackhawk and Vaquero revolvers it seems very straight forward. I don't see anything in this video to raise any concerns over tricky spots or things that leap away to freedom.

https://www.youtube.com/watch?v=UfOXBa8K8Ow

I would wash the brass and not worry about the inside of the revolver. I've fired hundreds of shots from my Old Army and have never needed to strip the internal parts for cleaning. Just my 2 cents.

What Praire Dawg said. I could not get my revolver apart for about 10 years (trigger/bolt spring screw was stuck) so I cleaned what I could, sprayed WD-40 down into the innards and called it good. Finally got it apart and had nothing but black sludge in the works but no rust. Lots of cap frags though.

My .45 Blackhawk is stainless. The grips are stags. I just pull the cylinder, cock the hammer, put it in the dish washer. Lube it up when dry. I did that with my stainless ROA, but not with the blued one I have now. I never detail stripped my cap and ball guns including my ROA which is a modified super blackhawk. I don't see the problem here.

Hot soapy water and compressed air. Oil vigorously.

I've been shooting a lot of BP in my Vaquero's and Black Hawk's. Every few hundred rounds I pull the grips, spray liberally with Ballistol and blow off with the compressor. Once a year they get a full tear down and I'm not seeing any ill effects.