I need to replace the fiber optic on my front site of my M&P Pro 9 mm (#178010). Does anyone know what the diameter is on these tubes.

I've never had to figure out the diameter on the fiber optic b/c I think they are all the same diameter. The difference between the different sights will be the height and width of the sights in addition to if you want a smooth or serrated sight. The 9 Pro I found needed a shorter front sight than the one that comes with the pistol.

I can replace the tube myself, it's pretty easy to do. When I mic the M&P tube it comes to 3.54 mm. When I mic my S&W 22 Victory tube it comes to 2.83. You can buy replacement material pretty cheap, but it comes in a variety of diameters.
Fluorescent Fiber

3.54mm sounds awful big. Are you measuring the rod or the lump melted over into a bead on the end?

My Dawson sights have 1mm inserts, Brazos 1.5mm.

The Novak front uses .060.

Anybody know size the 22 Victory takes?

Novak contacted me today. The front sight on the M&P Pro is .060". S&W also contact me today about the 22 Victory. It is .070".