Do they actually offer this? I didn't see any .17HM2 barrels on a quick check of the website.
Based on what I know about the .17HM2 cartridge, I wouldn't think this would be possible without some serious re-engineering, whether or not you added a stronger spring. Back when the cartridge was introduced, it was touted as a quick-n-easy barrel-replacement change for existing .22LR rifles, but when folks started to use it, they found that even with a stronger spring, the bolts in semi-auto rifles (a large portion of .22LR firearms are semi-autos) were opening too quickly and the case heads were bursting. As I recall, the only way they found they could get it to function safely and reliably was to add mass to the bolt, which killed much of the quick-changeability appeal. I believe Ruger 10/22s could still be converted fairly easily by adding a heavyweight bolt handle (another drop-in part requiring no fitting) to increase the total mass of the bolt assembly, but after folks found out it wasn't as easy to convert as originally advertised, interest dropped-off fairly fast. It's still a relatively easy barrel-change to convert bolt-action or other manually-operated rifles, but the minor accuracy improvement, greatly increased cost of the ammo (2x to 3x or more than .22LR), and lack of availability of conversion barrels/parts has combined to almost kill-off the cartridge.
Also, the .17HM2 gets it's power and dramatic expansion effects from velocity, and putting it in a short-barrel pistol would kill that advantage as well. The increased accuracy advantage would also be mostly negated in a small/light/short-barreled firearm with a relatively heavy trigger pull, so I don't think it has much of a future in this type of platform.
Sorry to be such a buzzkill/DJ-downer.