Larry, Not pointing fingers here, just asking -----
Are you getting the groups to the right from a rest or hand held.
I ask this, because years back everyone could out shoot me with my own handguns, to the point I sold them!
Wasn't until I did some 50' gallery shooting with a .22 - slow fire, timed and rapid - that I found out it was ME!!!!!!!!
My trigger pull/jerk pulled me off target every time - low left as I recall.
If your using a rest, then I really think there is likely enough adjustment in the rear sight to take care of the problem.
This is an adjustable rear sight Security isn't it??
Brownells has parts, and can likely supply a new sight blade, screws and springs if they are needed.
Hang in there, my Ol' and well used security is smooooooth and just a great shoot'in gun!
Keep em coming!
Crusty Deary Ol'Coot