Waywardson,
A repair probably won't be cheap, but, it may be your best bet.
That is if it can be welded.
I was a fair tig welder for many years, and I know I am nowhere near talented enough to weld such a small thin piece as one of the cylinder teeth. I am sure someone can though.
The lr cylinders for these revolvers are getting impossible to find
I have 9 H&R convertibles, and am always looking at more, and also at cylinders.
I have probably sold over 20 of these cylinders in the past few years.
I am constantly searching for them.
I still run into the mag cylinders occasionally, but the lr are rare.
I do have a mag cylinder that I will sell, and recently bought a lr cylinder, but I am not positive it is the correct cylinder for the convertibles. I took a chance when I bought it, and I won't know for sure what it fits until it arrives.
I know of NO place to buy a new or rebuilt cylinder.
Both of the mag cylinders I have are in like new condition. I don't believe either of them even shows any powder blast on the face, they don't look as if they have ever been fired .
So, I can help you with a mag cylinder, and possibly with the lr cylinder.
Jim
Here's a few pics
model 649 5.5" 1980
model 649 7.5" 1980
model 650 1980
model 686 4.5" 1980
model 686 5.5" 1980
Model 686 7.5" 1980
model 686 10" 1982
model 686 12" 1980
Model 676 12" 1980