H&R revolver

areas around the formed rim. Probably today they are infinitely better than days of old. The risk is gas leakage back toward the shooter. The recoil shield in a revolver prevents gas leakage and debris from reaching your face but can project it sideways to bystanders or body parts. Modern rimfire cases are pretty well annealed and very sturdy. I used some late WMR cases for "bushings" making something and man were they thick and hard to drill holes into.

If you note on rimfire revolvers, and older centerfire revolver designs, many chambers are built recessed for the rim. This is to give extra safety in the event of a rimfire case rupture of maybe the old balloon head rounds of yore. I think some old Colt revolvers (rimfire) had non-recessed cylinders. Relying on memory alone, and caution was given on high-speed modern ammo. Maybe someone has greater insight.

You "can" shoot the smaller diameter case .22 LR in a Magnum but as JT said you certainly risk gas leakage. You are NOT supposed to do it. The .22 Winchester Magnum Rimfire, WRF -Winchester Rim Fire, .22 Winchester Auto also, all have a conventional bullet (.224") seated inside the case and are greater in diameter than conventional heel type .22 RF (.222" diameter bullet - same diameter as the case body).

It is interesting to revisit.