I purchased a S & W 625 that has a SDM fiber optic tube front sight. The plastic tube is missing and I ordered one on e-bay. The sights that have holes all the way through call to heat up both ends of the tube, the SDM sight has one end that is drilled all the way through but the other end is a blind hole. Do you heat up only one end and pull it into the sight, or is the blind hole end glued in to hold the tube in ?

I have a couple of handguns with fiber optic sights, but am not familiar with your revolver and sight setup. I would not glue the rod (tube) because that will make it difficult to replace the next time it breaks. That's the downside of FO sights, IMHO, in that they are somewhat fragile. I carried replacement rods for my competition gun.

Again, without knowing the configuration of your sights, I suggest that you cut the rod to the correct length, then insert one end into the blind hole and heat the other end with a match or lighter. That end will expand slightly and hold the rod in place. May take a couple tries to get it right.

That's how it worked with my FO sights, although they were open on both ends. Others here who are familiar with your specific firearms may have better advice.

SDM frequently break their FO rods because they crimp the sight down onto the rod to hold it in place and usually crack the rod in the process. When I used SDMs I'd drill the hole for the FO all the way thru so I could heat both ends.

Then I found .100" wide FO fronts here and quit using SDMs.
Custom S&W revolver front and rear sights-LOCKED DUE TO LENGTH - Protocall Design - Brian Enos's Forums... Maku mozo!

Thanks tomcat, I will try removing the sight and drill it out. I tried a .060 fiber optic rod and it would not fit in the back of the sight, like you said they must have crimped the original in.

The .060 fibers are 1.5mm. The best drill bit for that one is 1/16 or .062.

Some sights, like mine, are .040, or 1mm. The best drill bit to use for 1mm is a #57 which is .043. The holes need to be a bit oversize, as the fibers are not an exact size, but a little bit variable in diameter.

The best fix is in post #3, drill through and melt both ends. If only one end is melted, it won't stay in.

Thanks toolguy, the #53 drill at .0595" is too small and was worried that 1/16 at .062" would be too loose. I miked the glass rod and its .061", I will try the 1/16 drill. Thanks Again All !