When the HMR first came out, a few daring souls converted the Grendel .22 Mag autoloaders to the new round. They had issues, big issues, with the guns firing out of battery, just like Remington did with their 597 rifles, and most everyone else's .22Mag autoloading rifles.
It's not a good idea, and whenever someone gets a wild hair and tries it, they have innumerable problems. If you want an HMR handgun, buy a Single Six or a Taurus, and just forget about an autoloader.
