My dad built an autoloading 17 HMR rifle out of a 10/22 22 Mag. He put an aftermarket stock on, and a carbon fiber barrel, along with a heavier bolt and spring. He never shot it. I inherited it from him and replaced the trigger. It shoots like a dream. The autoloader needs more mass in the bolt and a heavier spring than a standard 22 Mag, or the brass can separate near the case head.
A buddy of mine built one, too. A genuine fancy walnut stock, yadda, yadda, and it worked fine, until it didn't, when his granddaughter was shooting it She got a faceful of gas and a bad attitude about shooting. Ruger quit production of the 10/22M because of out-of-battery firing. The bottleneck case of the HMR will be even more susceptible to such shenanigans, especially in a pistol.
Again, it's a bad idea. A PROVEN bad idea.
