Formula for Height of Front Sight

[Leif]

I'm no mathemetician, but I wonder if there is a formula for calculating the proper height of a front sight for a rifle using aperture sights? Something that takes into account height of the rear sight, barrel length and muzzle diameter, distance to target, etc.

I'm trying to set up a Remington 700 BDL .22-250 sporter with sights and was hoping for something better than trial and error. Any input appreciated. Thanks.

 

[PetahW]

The proper total front sight height (including ramp if any) equals the height of the aperture (midway in it's elevation adjustment range) above the bore C/L, minus 1/2 the muzzle OD.

( TFSH=AH/CTR-50%MOD )

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[Leif]

Thanks, but shouldn't it also account for range?

 

[Chipperman]

Not if the rear sight is adjustable.
If you have a fixed rear sight, then it needs to account for the range you will be shooting and the ballistics of the round.....

But who would want a fixed rear sight?

 

[Jimro]

The idea is that you set up the front sight as completely fixed point so that the rear sight can zero for windage and elevation.

On a rifle like the M16 where the front sight post is adjustable, it is only adjusted to get the sighting system zeroed to an individual rifleman, and it is never touched after that until the weapon is issued to another rifleman.

Jimro

 

[PetahW]

[shouldn't it also account for range?]

That is why the measurements are taken, and the calculations made, with the peep in the middle of it's elevation adjustment range. (aka: "midway in it's elevation adjustment range", above)

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[curmudgeon1]

Why would one want to zero in a rifle at the mid-point of the elevation range; wouldn't it be more logical to set the elevation at it's lowest setting before setting the height of the front sight ?

 

[Jimro]

Because different loads will have different zeros. One load may bottom out the rear sight, another may use up all but three quarters of adjustment. This is for a sliding ramp rear sight. For a competition micrometer style there is way more adjustment.

Jimro

 

[PetahW]

It makes little difference whether using a sliding ramp rear barrel sight, a flip-down barrel sight, a receiver peep sight, or a tang peep sight.

Sight height calculations are ALWAYS made with the rear sight in the middle of it's various adjustment ranges, so as to give maximum flexibility of adjustment when zeroing upon firing, as posted above by Jimro.

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[curmudgeon1]

So..... to summarize.....should we be advised that when zeroing-in a new rifle, the front sight elevation and the rear sight elevation should be at their midpoints of travel range when starting out ?

 

[PetahW]

No, you shouldn't.

Rather, you should be advised to center the rear sight when CALCULATING what the proper height of front sight would be, to buy/make/install - and not necessarily to zero the piece.

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[curmudgeon1]

Ah, okay.