It's not safe. The dimensions are different and the .32 H&R Mag is a higher pressure round. Other people may be doing it on YouTube, but people do a LOT of stupid stuff on YouTube!
I have also come to the belief that almost anything on YouTube is something to put at the top of your "Don't Do" list.
The YouTube videos from Hickok45 are usable. Just saying.
First off, minor correction to rsayloriii's first post. The .32 S&W/.32 H&R rounds use the standard 7.62x38R cylinder. The only conversion cylinder available is for .32 ACP.
Really? I've never heard of that before, just the .32 ACP conversions.
Aftermarket cylinders for .32 can be installed, allowing them to safely fire .32 H&R