S&W Rear Sight blade help needed

[Chuck Perry]

I just put a Hi Viz front sight on my 5" 625. I'd now like to add a V notch rear sight blade. In checking Brownell's, there are several different blades in stock and I can't figure out which one to order. They have three: .122", .160" and .190". What does this measurement reflect and how do I decide which I need?

 

[madcratebuilder]

Measure the blade on the revolver now.

 

[rcmodel]

If the gun still can be adjusted to shoot POA with the new front sight, measure the old one and get the same height V-notch one.

Be aware that changing the rear blade almost always involves ruining the windage screw & nut. They are staked together at the factory and don't want to come apart without something getting messed up.

Best be sure and order a new windage screw & nut when you order the new blade.

rc

 

[Chuck Perry]

Thanks guys

 

[LubeckTech]

Before you take the windage screw out check on the reassbemly procedure - I think the end of the new screw needs to be peened so it won't come out if adjusted too far. Brownells or other places probably have instructions or downloadable videos. Also a spare detent plunger and spring would be a good idea as they are both easily lost. They are very inexpensive, less than the postage for replacements and come in handy. When you are removing the windage screw go slowly and watch carefully for the plunger which is located in a hole in the windage screw.

 

[Chuck Perry]

This is starting to sound like a PIA better left for the gunsmith. Unfortunately, it doesn't sound like I can figure out which size blade to order without disassembling the sight. Maybe I'll just order one of each, hand them all to the smith, and return the ones I don't need when he's done.

 

[Oro]

Unfortunately, it doesn't sound like I can figure out which size blade to order without disassembling the sight. Maybe I'll just order one of each, hand them all to the smith, and return the ones I don't need when he's done.

It is a little bit of a PITA, actually. But you need to know this:

The windage screw/nut are non-reusable. You have to buy a "rebuild kit" which includes those two items and I think also the detent plunger/spring. They are about $10, that's in addition to the blade itself. Sometimes they sell the blade and kit for $16, I think. They have some right on the S&W website last time I looked a while back.

The easiest thing to do is to call S&W and ask them. They will know precisely which size blade you need, and have the rebuild kit included or on hand. BTW, .160" should be the correct blade height for a 4 to 6" K, L, or N frame.

If you want to measure the sight blade without taking the blade out (remember, you can't put it back in w/o the rebuild kit), what you do is run it all the way to the left. The blade will hang out of the tang enough to measure it with calipers easily. Just count the number of "clicks" and then you can re-center it precisely. Or just order the .160" - it will be close enough. The S&W size is actually .147" I believe, but there is variation around that as that is the nominal size of the stamped piece and they vary a little bit. .160" is probably a universal replacement and is plenty close that the elevation screw will compensate.