Regards, JimHnSTL.

Suspect you already know: A V-block 77/22 with the proper bottom metal can be configured for any rimfire cartridge (excepting the WSM). Numrich has the trigger guard for the .22WMR, also works for the .17HMR:

https://www.gunpartscorp.com/products/516220

A minor fitting to either the bolt or the ejector that's integral to the trigger guard may be required.