Colt Python KAGE Installation should be done by a qualified gunsmith. 

Red Loctite should be used on all screws.

Ensure weapon is clear.

Remove front sight.

You MUST heat up the front sight screw hole with a lighter for 5 seconds to clear factory loctite.
Insert smallest included allen key & turn counter clockwise.
Remove rear sight.

Use 1/16th punch to remove the roll pin from left to right, then Flat Head to remove rear sight screw.
Install top rail onto Python 

Secure with included rear screw until SNUG
Slide pre assembled bottom rail & comp onto Python ensuring alignment

(3” versions = Insert long screws up front / Short screws in the rear ensure top rail is fully seated & holes align with bottom rail (may have to squeeze top rail to align).
4.25” & 6” versions = Remove Installed Rail Screws & Ensure top rail is full seated & holes align with bottom rail (may have to squeeze top rail to align.)
Install all button head screws ¼ of the way, then all ¾ of the way.
Tighten Top comp screw ¾  of the way.
Tighten all button head rail screws until SNUG.
Tighten top comp screw until SNUG.