Different barrel lengths require different height sight blades. If you haven't changed a blade before, a full kit includes instructions. It isn't difficult at all, BUT, when you back the windage screw all the way out the detent plunger and spring (which are very TINY) may fly away to location unknown unless you capture them. Hint, put it all in a large clear plastic bag before backing the screw all the way out so it won't get away. Good luck.

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H Richard
SWCA1967 SWHF244