The shim described here is a temporary fix which could put your gun in the field for years but there is a similar method that is a permanent fix.
You could have the gun repaired using a spray welding repair technique. This a system of depositing a thin layer of material onto the hinge and then filing it to fit properly. A competent gunsmith, using correct welding techniques, will easily repair this problem. It works in the same way as the shim; it lasts longer but costs more.