Widening rear sight notch

The Bomar type rear sight notch on my new 1911 is too narrow for old eyes like mine.*  When aligned with the front the light on either side of the front forms a narrow sliver, which may be enough for some but not me - especially at the local indoor range with low light levels.  Previously I modified the rear sight notch on my SW41 and decided to do the same on the 1911.

I used a diamond abrasive plate that is part of a knife sharpening kit:  

https://postimg.cc/phyK2c1R

There is no abrasive on the plate edges and it was used to file each side of the notch wider - keeping the 45 deg angle open to the front so the rear of the sight is a sharp silhouette. Once the notch was wide enough the sight was touched up with bluing (blacking actually)  with this:

https://postimg.cc/sBjpLgYB

Here is the finished work:  

https://postimg.cc/NK4XRv3Q

Doesn't show well in the pic but to me a big improvement in sight picture

https://postimg.cc/LqxzFFDx

*Unlike the Bomar my FWB P44 air pistol has a fantastic rear sight with adjustable width blades, which I set nice and wide

How wide did you end up making the notch?  This came up in conversation at a match this weekend and I think I could benefit from doing it.  I’d be curious how wide you made the notch and how you settled on that width.  I suppose it would matter how wide the front sight is too since it’s a relationship between the two.  I’m looking for a little guidance before I jump into modifying my guns.

Thanks.
John

This has no empirical value but I widened it until the light bars on either side of the front sight were close to the same width as the front sight.  I tried to approximate the sight picture of my FWB P44 air pistol, which has adjustable rear sight notch width.

It's kind of liberating - like "the government says you can only see this much" - but you can (and should) take control

Not that it made much difference because the range I shoot has poor lighting and irons are very hard there, and for that matter anywhere, for aged eyes

Just measured FWIW (with inexpensive calipers   ):

Rear sight notch  0.19"
Front sight width 0.125"

NB went slow with removing material, checking the sight picture along the way and stopping when it looked "right".

I did the same thing on my SW41 several months ago;

https://postimg.cc/VdBbKvdr

I also have a 41 barrel with a dot, which I shoot much better so the iron-sighted barrel is largely neglected

John Dervis wrote:How wide did you end up making the notch?  This came up in conversation at a match this weekend and I think I could benefit from doing it.  I’d be curious how wide you made the notch and how you settled on that width.  I suppose it would matter how wide the front sight is too since it’s a relationship between the two.  I’m looking for a little guidance before I jump into modifying my guns.

Thanks.
John

Your arm length and the sight radius will affect the appearance, so you can't use someone else's measurements, except as a guide. I agree with the "go slow and check often" advice. That's how I did it.

And my Harbor Freight needle file with a "safe edge" isn't really entirely smooth and filed a little groove in the bottom of the notch. It isn't a big deal, but if you are particular about the appearance of your guns, make sure you use a good file.