Green River stainless 17 HMR .920 for a 77-22 Ruger. I really don't know what it would take to convert a 22lr to 17HMR. I think this barrel has been discontinued. Never installed. Contact me for pictures. $100 shipped.
If it's an HMR it's for the 22 magnum length actions. An HM2 would go an. 22LR action. It's a simple swap that just requires switching the barrel. I switch my 77/22 LR to 17 HM2 whenever I can find the ammo and then back to 22 LR when I run out.