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Enos' Ideal Front Sight Width


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The following summarizes a spreadsheet designed to calculate the ideal width of a front sight based on Brian Enos' suggestion that the "perceived" (not actual) light bar on either side of a front sight should be about 50% of the front sight's width. He believes this gives you "enough room to work with", but not too much.

It is important to note his emphasis on "perceived". This refers to the fact that the actual rear sight opening (which is closer to the eye) is perceived a bit wider out by the front sight (farther from the eye. The following spreadsheet and formula account for this and will allow you to select an Enos front sight without need for experimentation.

The following formula requires these measurements:

1. front sight width, and radius (distance from eye)

2. rear sight opening, and radius

The formula for the ideal front sight width is:

FS = RS / RR * FR / 2

FS = ideal front sight width

RS = rear sight opening

FR = front sight radius

RR = rear sight radius

Easy to use, no need to experiment.

The calculated ideal width is - for all practical purposes - quite accurate enough for choosing a front sight based on a specific rear sight opening. For those of you who'd like a copy of my handy dandy spreadsheet - it's fun to play with - drop me a PM and your email, I'll send it to you...

For example here's a stock G-34, stock plastic sights...


Front Sight (width) 0.140

Rear sight (opening) 0.125

Rear to Front (distance) 7.50

Front Radius (distance) 25.75

Rear Radius (distance) 18.25

Front Apparent Opening 0.176

Perceived Light Bar (%) 20.6%

Ideal Front Sight (width) 0.088

(for 50% light bar)

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I'd suggest changing out the rear sight width, based on any given front wight width. (solve for RS)

People choose front sight size for a variety of reason. Whatever they may choose, the variable then becomes the rear sight notch width.

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People choose front sight size for a variety of reasons. Whatever they may choose, the variable then becomes the rear sight notch width.

I'll take your word on that. As an older guy, I kinda like the Glock stock (0.140) front sight, it grabs my focus. Turns out that a 0.200 rear would then work (and Ameriglo happens to make one). My spreadsheet (available for a PM) can work it either way and it's easy enough to rearrange the formula... if I'm not mistaken:

FS = RS / RR * FR / 2 (solve for front sight)

RS = FS * RR / FR * 2 (solve for rear sight)

FS = ideal front sight width

RS = rear sight opening

FR = front sight radius

RR = rear sight radius

Flex, a question. Just what are the common front widths chosen, and the reasons for doing so?

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Well...one reason is as you stated...

A big fat front sight (like a 0.140) is easier to see and pick up (especially with iffy eyesight).

For close up work, like most IDPA stuff, self-defense, etc... a bigger front sight might prove an advantage.

If I am shooting 8in round steel plates at 25y (Bianchi/Action Pistol)...I want a smaller front sight....one that gives more feedback in relation to the target. (and doesn't just flat out cover up the target)

We see the occasional 35y...40y....50y shot in USPSA matches (the A-zone is 6 wide x 11 inches tall).

Some applications need FS width to accommodate a fiber optic or tritium vial.

Some applications favor a front sight that might not break off so easily.

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Hello: I like the front sight width to be between 0.090-0.105" and the rear sight cut to be 0.115-0.140". It depends on the sight radius and what game I will be shooting. Like Flex said a small plate at 30-40 yards is hard to see with a 0.140 front sight. I also like the green fiber insert on the front sight 0.060" diameter. I have used a 0.070" front sight on a 6" STI 2011 I built and it worked fine with a Bo-Mar rear sight. I really think it comes down to what you are used to seeing. Thanks, Eric

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Verrrrrrrry interesting, thanks.

For the math challenged among us, I took a min with my spreadsheet and got the following.

For a 7.5 inch sight spread, 23.5 inches to FS:

Front Rear

.090 .128

.100 .142

.110 .156

.120 .170

.125 .177

.130 .184

.140 .198

These would be ideal "Enos" 50% light bar combinations for a G34, a fairly typical gun, and for a typical sight radius. Flex's makes some interesting observations re target coverage - you might want to check this link for a formula on target coverage by the front sight.

A standard (0.140) fat front sight covers:


At 25 yards = 4.7 inches

At 15 yards = 2.8 inches

At 10 yards = 1.9 inches

At 50 yards = 9.4 inches

Don't even ask me what a "big dot" covers, lol...

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  • 1 year later...

I don't mean to dig this up but it just made me curious how the whole Glock line stacks up with the standard front sight widths.

ESR- Extra Sight Radius achieved by setting back from the dovetail like most after market sights. Constant .25 was used.

AL- Arm Length Constant 18.5 was used. I measured my self at 19, but split the difference a bit.

FSW- Front Sight Widths. Standard easy to find widths were used.

FSR- Factory Sight Radius from Glock.com G26=5.67 G19=6.02 G17=6.49 G34=7.56

IRSW- Ideal Rear Sight Width = FSW*AL/(AL+ESR+FSR)*2 which was derived from RS = FS*RR/FR*2


0.11	0.1667
0.115	0.1742
0.125	0.1894
0.14	0.2121

0.11	0.1643
0.115	0.1718
0.125	0.1867
0.14	0.2091

0.11	0.1613
0.115	0.1686
0.125	0.1832
0.14	0.2052

0.11	0.1547
0.115	0.1617
0.125	0.1758
0.14	0.1969

My personal conclusion: Standard widths of Heinie, Warren and 10-8 are a bit narrow as the largest of them is .156

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I annot speaks as to these calculations, but I know that I personally see the Warren Sevigny sights on my G-35 a whole lot better than I could see the factory plastic front and adjustable rear. My 58 year old eyes just "see" that FO front better, and I really seem to be better able to get my sight picture with the extra "light" on both sides of the Sevigny's. I have used Heinie Straight 8 night sights on duty Glocks, but I just seem to be better able to shoot the 35. I cam not skilled or knowledgeable enough to tell you if it is the narrower front, the wider rear. longer sight radius or a combination of all of them. I can tell yu it works for me.

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  • 7 years later...
2 hours ago, SSGGlock said:

Any other updates on this?

On today's Shooters Summit, Eric Grauffel says he prefers a wide front sight in bright light. He points out that is preferred by Bullseye shooters for accuracy. He also does not use "the big squeeze" for grip. He uses a push-pull (from an isosceles stance, not Weaver). His trigger finger contacts the trigger between his first and second knuckles. He emphasizes the importance of finding what works for your hand, gun, and preferences and not force yourself into whatever someone is telling you is the "right way".

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16 hours ago, SSGGlock said:

I have a G34 with a .156 rear and a .115 front, but to me there seems to be too much light gap.

As stated above the perception of what you're seeing is what usually makes a certain set of sights better for one person vs. the next.

I've found for "MY" eyes on a 5'' 1911/2011 gun ..010 what has been called light bars on either side of the sight works great.

the exact measurement is unknown by me, sure some of y'all will figure it out, but I generally have a .020 wider notch in the rear sight than the front sight blade width.

Again for me its an easy way to figure what to buy . i.e. rear notch width .130 front sight blade width .110.

Once again for me allows speed and accuracy

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  • 2 weeks later...


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