A good shortcut -- and savings of time and money -- is to figure out the brand of the fiber optic sight, check that company's web site, and order some replacement "fiber optic" plastic tubes.

A quick look at the S&W web site indicates these may be made by Hi-Viz, as Hi-Viz fiber optic sights are described on the S&W web page as being on one of the PC Shields.

The fiber optic (okay, colored plastic) tubes are cheap and can be replaced pretty easily.

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S&W Rover