Smaller aperture for Enfield No.4 sight - easy fix

[higgins]

The lens I chose to have implanted for cataract surgery left my near vision up to about 5 feet in need of correction. Rifle front sights are just far enough away from my eye that I need help from a small target-size aperture or notch rear sight to bring it into focus. The front sights on my Enfields were blurry, so I set about finding a fix for it. I thought about drilling and tapping the rear sight slide for a Lyman or Williams target aperture, but didn't want to alter the rear sight unless I had to. I turned my attention to the larger hole on the front of the slide. I knew I had something with a small hole in it among my misc. junk that looked like it would be a snug fit in the hole on the front of the slide, and I finally found it. It is a hard rubber fuel valve seat for a Tecumseh lawn mower engine carburetor. It fits the hole in the front of the slide like it was made for it. The hole in the valve seat (about .060-065) is not that much smaller than the aperture on the back of the slide, but it is just small enough, in combination with the tunnel effect (?) to bring the front sight into almost clear focus-certainly much clearer than it was beforehand. I'm sure those of us who have collections of small engine parts or other small items with holes in them will come up with other fixes. I placed a couple of very small dabs of super glue on the valve seat so it wouldn't work loose and fall out under recoil and handling. After 30 rds of full power surplus ammo it's still in place. An even better fix would be something with a bit smaller hole in it that's threaded that would fit that hole with very little enlargement and be held in place with a bit of threadlocking compound. What I like about this fix is that it's cheap and does not alter the rear sight. A complete carburetor kit including this valve seat is $4.50 at my local small engine shop; being really cheap and a packrat, I had kept this used one when I installed a new one in one of my mowers several years ago. The attached photos show the seat next to a ruler (colored with a Sharpie so it will show up in the photo) and the seat installed in the Enfield sight; I colored it black with a Sharpie after I installed it, so it's hardly visible.

[JeffinNZ]

Brilliant!

[ph4570]

Well done.

[303Guy]

Great idea!

That's interesting. My rifle's sight looks smaller than yours - not the aperture but the relief behind it, meaning that insert looks like it won't fit mine. Did they come in different sizes?

[higgins]

I don't know if they come in different sizes, but they probably do. However, I was told by the parts vendor that by far most Tecumseh motors use the same kit. The outside diameter of the valve seat I used is about .190 inch. Between the variety of sight slide manufacturers over the life of the No.4, sight tolerances, and tolerances in Tecumseh carburetors (the seat I used was a used one, so had sized itself to the hole it was seated in), I may have just gotten unbelievably lucky. Another fix that has come to mind would be to machine a piece of brass with about an .05 aperture in it to be a snug fit in the hole and secure it with a couple dabs of super glue. If it falls out you haven't lost much, assuming you know someone who can machine it cheap. If you know a small engine or even large engine mechanic describe what you're looking for - someone in those trades is bound to be aware of something made of brass, aluminum, or other metal that has a small hole alread in it that could be modified to serve as a sight insert.

[303Guy]

I have a lathe but so far I am lucky to have 20/20 vision provided it's not too close in low light. My No.4's aperture seems about right for me. I'm wanting to shoot target with it using paper patched boolits at one of our local clubs. I might use that trick on the ladder aperture. I'm sure super glue would work just fine. So would epoxy. I've used epoxy to glue scope mount bases onto the action!

[Four Fingers of Death]

Brilliant! I must check mine out when I get home.

[Junior1942]

Please edit that and add paragraph breaks. It's too hard to read.