Revolver Rear Sight Blade Information Thread

[matteekay]

This thread has been a long time coming. First and foremost, a million thanks to Toolguy for sending me a bunch of blades to measure and test. The genesis of this thread was me trying to figure out what rear blade would work with a custom front sight that I put on a 15-3. The one thing I couldn't find is measurements beyond the height of the blade; given that the notch depth and its relation to the blade height will largely determine POI, this was problematic. So, here we are!

Part 1 - Measurements
All measurements taken with digital calipers. They are Harbor Freight, so consider these to be... close-ish, lol. All blades are new S&W units.

These are the measurements I took from each blade:
Overall Height: Measured from the bottom of the threaded base to the top of the blade.
Actual Blade Height: The blade section.
Notch Depth: Measured from the top of the blade to the bottom of the notch
Notch Width: How wide the notch is
Notch Bottom: Measured from the bottom of the threaded base to the bottom of the notch. This is important as it will represent the absolute bottom of the sight.


.106" Blade
Overall Height: .296"
Actual Blade Height: .108"
Notch Depth: .057"
Notch Width: .131"
Notch Bottom: .239"


.126" Blade
Overall Height: .306"
Actual Blade Height: .125"
Notch Depth: .051"
Notch Width: .125"
Notch Bottom: .255"


.146" Blade
Overall Height: .330"
Actual Blade Height: .145"
Notch Depth: .077"
Notch Width: .125"
Notch Bottom: .253"


.160" Blade
Overall Height: .347"
Actual Blade Height: .161"
Notch Depth: .077"
Notch Width: .125"
Notch Bottom: .270"



Part 2 - Point of Impact Testing
For the next part of the test, I put each blade onto my 15-3 and fired six rounds. Please remember that these are only rough guidelines as barrel length, front sight height, load, and distance will all affect POI.

Test Overview:
- Gun used was a 4" 15-3 with a custom front sight
- All shots fired from a sandbag at 10 yards
- Six shots fired with each blade. I removed any outliers (more than 1" away from the main group) and averaged the rest to determine these numbers
- Load being used was a .38 Special (158 Berry's plated RN over 3.7 grains of 700-X)

Results (approximate and averaged):
.106" Blade: 3.0" above POA
.126" Blade: 1.75" above POA
.146" Blade: .125" above POA
.160 Blade: 1.875" below POA



Part 3 - Factory Equipment
Thanks to user GunarSailors for posting this. This spec sheet shows what revolvers came with which rear from the factory.

[matteekay]

Hopefully folks find some value in this!

[Protocall_Design]

This is a valuable resource for everyone. Many thanks to Matteekay for putting in the time and effort to bring all this together for us!

[catadjuster]

Thanks for this info Matteekay - could come in handy for lots of folks.

[matteekay]

Sure thing, guys, glad to do it. What I *won't* be posting is a picture of my groupings - with no windage nut installed, things tended to spread out laterally, lol.

[bigchuck83]

Great post and I'm sure it will be helpful to a lot of us .


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