The glue solutions are fairly effective.

In situations where maintaining the appearance of originality are not a concern the most effective long term fix is to build steel pillars and fit to length. They capture the screw and give a solid stop. Last the remaining life of the gun.

I did exactly that to the front and rear tang screws on the the two M21’s I competed with. Had no problems related to tang screws or triggers after that. Wish I had done it years sooner.