Fitting the proprietary trigger guard took quite a bit of experienced work fitting both the lever and new guard. I don't see any reason to explain because I have the only one left.
The trigger was the first modification I felt the #10 NEEDED to built a fine hunting rifle. The original trigger shoe is tiny, at an awkward angle and does not have a great sear interface. Look at it. The bench made triggers improved all of these issues and looks exponentially better. Also the recesses safeties can crack at the rear of the action when case hardened and the drawbolt is over tightened. I would never case harden a 4140 high carbon #10 action. I know it was done a lot but that doesn't make it a good idea. Hagn actions were made from relatively low carbon 8620 for exactly that reason. This was a well known option that Don Allen chose to ignore.
A case hardened, small Hagn actioned rifle in 7x57 by Jerry Fisher with engraving by Barry Lee Hands