Front blade/Rear notch width relationship

[longfellow]

I've read Nygord, Yur yev and others mention the popular front/rear ratio as either 1:1:1 or 1:2:1.
I am assuming that this is "perceived" ratio and not actual measured ratio. Correct?
If so, then when I trig it out, I get, for example with the 1:2:1 ratio sight set, a rear notch that should be .190 (for my particular sight radius and front width).
All of the current and older target-style rears come with much narrower notches. I just bought a genuine Bomar BMCX for a wad gun I'm having built and it's notch is .112.
If the ratios are NOT perceived but actual, then the rear notch would calculate out to be even wider.
I put my rear on a surface grinder and opened it up to .165 which looks pretty good to me but is still far shy of 1:2:1 with my unmodified front.
Were all you guys opening up your rear notches or just ignoring the recommended relationships and leaving the rear at the original .112-.125 width?
I am asking because I would occasionally like to have a different notch width based on lighting conditions and having to break the castle nut staking every time is a hassle so I was looking for options for an adjustable rear sight for a 1911 which offers replaceable blades. Wilson Combat has exactly this which requires custom milling of a bald slide so retrofitting is not an option but I might consider it for the new wad gun. If there are any other options for fitting out a 1911 with adjustable sights that have replaceable rear leaves, including any kind of fitting out of international sights in some way, I am open to suggestions.

I posted in this forum rather than in Bullseye for obvious reasons; you guys live open sights.

Comments please?
Thanks,
Ed

[David M]

The Foresight is 70-100% of the apparent width of the target black. (above Foresight is 70% of black width)

For Precision shooting a 2:1 Rear sight (as above, 1:2:1)
The Rear sight notch is twice the apparent width of the Foresight.
Note the sight depth makes a square image of the foresight. (easy for the eye to pick).

For Rapidfire increase the ratio to 3:1, (1:1:1)
helps to acquire the sight quickly and the precision is not needed for the bigger target 10 ring.

To open up a rear sight, very careful handwork and a good eye with a new/sharp square needle file is required.
Grind the teeth off one face of the needle file to make a smooth safe edge to help keep the corners square.
Re-blue the sight when finished.

[Gwhite]

I use the "symmetry" approach recommended by the Olympic Training Center coach at a clinic several years ago. The idea is to maximize the symmetry of the image and train your brain to think of it as one image you try to maintain, and not three moving parts. The more symmetrical the image, the easier it is to train your brain to use your muscles to maintain it.

You want the perceived width of the front sight to be close to that of the width of the black. The gaps on either side of the front sight should match the gap between the black and the top of the front sight:

Sub-Six Hold.jpg (18.06 KiB) Viewed 4005 times

The size of the gaps depends on your hold & personal preference. You never want the front sight to wander off so far that it touches the inside of the rear notch. I've also heard a wider notch width recommended for older eyes. Of course, the wider the rear notch, the lower you will need to hold, but this is usually pretty minor.

I also wouldn't get too obsessed about it. Far more points are lost due to poor trigger control than a slightly "imperfect" sight picture. Lots of people have been shooting very good scores for decades with whatever the manufacturer throws on the pistol. Use the time you would spend with a file on dry firing, and the money for fancy sights on training ammo...

[longfellow]

Very interesting concept regarding symmetry. I like it very much. In fact at my skill level I have to work on enough as it is so I really don't put much thought in to the space above my sight set and beneath the bull and it seems as if my brain wants to put about the same amount of space here as is on either side of the blade - exactly what you are saying.

I dressed a surface grinding wheel to the width that I now have so a perfectly square and straight notch is not an issue.

So you are all opening up your rear notches as I suspected then.

Does anyone have any thoughts on how I can outfit a 1911 with an adjustable rear that has easily exchangeable blades? Custom machining is not an issue as my builder will be starting out with a completely bald slide. If there were a way to mount a set of really good sights from the world of Olympic Free or Rapidfire guns, I would seriously consider it.

[Gwhite]

You could try to mount an adjustable width sight from the likes of Benelli or Pardini, but they will be very large, and probably require a super tall front sight. Your bet bet is probably to find a small sight similar to the older Hammerli air pistol ones (which are huge) that have a quick swap blade with different widths.

You are spending a lot of time & energy on something that you will set once & likely not touch more than once every few years (if that). I have several pistols with adjustable rear sights, and some fixed ones I've machined to a width that suits me. I haven't touched ANY of them in recent memory.

The most that might make sense is two interchangeable blades, one for bright days, and one for indoors.

I bet Brian Zins doesn't worry about constantly tweaking his rear sight width, and neither should you....

[thirdwheel]

Be aware that if your back sights go too wide they will be in your peripheral vision and not in your high intensity macular vision, this can be exacerbated by the use of a wide front sight - my preference. If I then use 1:2:1 I loose the rear sight out of my macular vision so bring them in. On rapid fire I use a narrower front sight to give wider gaps and faster sight acquisition but the rear sight although in a slight blur is in my macular vision. But once set they are not touched again and I just get on with it.

[Rover]

Just as a thought....many guns come with an extra rear sight blade. It usually is too small, therefore useless.

This is the one you want to experiment with. In my personal use, I have taken a 3/16" chain saw file to it. These are cheap at a hardware store, and are not tapered. This gives you the "Russian" half-moon sight that was so successful for them.

[Coolmeester]

If hold is good enough you can shoot with very narrow notch.

[longfellow]

Thanks for the tips folks.
I'm pretty sorted out I think, based on good results and a comfortable but still precise sight picture, with a 3.0mm front and a 4.0mm rear notch.