Chassepot 1866 sites

[GregLaROCHE]

I have been trying to master a Chassepot 1866. I finally got down making paper cartridges for it, but now I need to shoot it at 50 meters (50 yds), because the range where I can easily shoot is only that long. I bought the rifle from someone who did quite well with it at 100 meters. The problem is it has a lot of adjustments for long range, but at the minimum, it’s one meter at least high at 50meters. I don’t want to do anything to alter the gun that can’t be undone. My thoughts are to add some epoxy paste to top of the front sight to lower the point of impact. Is there a was to calculate how much appropriately to add? It should be zeroed for 100 meters and 50 being half that, I suspect that the boolit is at around the apex of it’s trajectory. Does there exist a formula to calculate this? Otherwise, I’ll put on a significant amount of epoxy and start filling down until it gets close.
Thanks

[Mk42gunner]

I found this on Brownell's website. It is in inches, but there is no reason you couldn't use metric.
https://www.brownells.com/aspx/learn...higher%20sight.

It should get you close anyway.

Robert

[GregLaROCHE]

I found this on Brownell's website. It is in inches, but there is no reason you couldn't use metric.
https://www.brownells.com/aspx/learn...higher%20sight.

It should get you close anyway.

Robert

That would be great, but Brownells always directs me to the French homepage, so I can’t see anything on the US site. Is there anyway you could copy the information and post it or PM it to me?
Thanks

[hawkenhunter50]

That would be great, but Brownells always directs me to the French homepage, so I can’t see anything on the US site. Is there anyway you could copy the information and post it or PM it to me?
Thanks

Correcting Sight Height
If your rifle or pistol is shooting high or low, there is a formula you can use to determine what the correct height for your sight should be.

Terms
Amount of Error: Measure in inches the distance from the bullseye to your shot.
Sight Radius: Distance in inches from the front sight to the rear sight. *
Distance to Target: The distance in inches from your shooting position to the target.

Note: Be sure that your rear sight is at its mid-point before you shoot.

Formula

Amount of Error X Sight Radius
= Sight Correction Needed
Distance to Target
If you are shooting low, you would replace your front sight with a lower sight, and conversely, if you were shooting high, then you would replace your front sight with a higher sight. Add or subtract the number of thousandths needed to the actual height of your sight and you will have the correct height of the replacement sight.

Example
At 100 yards, your shot is 6" low and the distance between your front and rear sight is 19.5".

6 X 19.5
= .0325
3600
Since you are shooting low, you would need to lower your front sight by .032".

* For rifles, you measure the front sight height from the bottom of the dovetail to the top of the sight. For pistols you measure the height of the blade only. This is true unless stated otherwise in the sight specifications

[Mr_Sheesh]

If you (or anyone else) is missing the Imperial to Metric conversion formulas:

Inhces to mm, multiply by 25.4
mm to Inches, divide by 25.4

Hope that helps someone

Also, "measure twice, cut once" LOL

[GregLaROCHE]

Correcting Sight Height
If your rifle or pistol is shooting high or low, there is a formula you can use to determine what the correct height for your sight should be.

Terms
Amount of Error: Measure in inches the distance from the bullseye to your shot.
Sight Radius: Distance in inches from the front sight to the rear sight. *
Distance to Target: The distance in inches from your shooting position to the target.

Note: Be sure that your rear sight is at its mid-point before you shoot.

Formula

Amount of Error X Sight Radius
= Sight Correction Needed
Distance to Target
If you are shooting low, you would replace your front sight with a lower sight, and conversely, if you were shooting high, then you would replace your front sight with a higher sight. Add or subtract the number of thousandths needed to the actual height of your sight and you will have the correct height of the replacement sight.

Example
At 100 yards, your shot is 6" low and the distance between your front and rear sight is 19.5".

6 X 19.5
= .0325
3600
Since you are shooting low, you would need to lower your front sight by .032".

* For rifles, you measure the front sight height from the bottom of the dovetail to the top of the sight. For pistols you measure the height of the blade only. This is true unless stated otherwise in the sight specifications

Thank you. This is exactly what I was looking for. However, I don’t fully understand the calculation. Where do you account for the distance to target? Also, I don’t know what the 3600 is or how it enters into the equation. Can you give a more detailed example please?
Thanks

[Mk42gunner]

(Amount of error X Sight radius) / Distance to target = Sight correction needed

A simple little algebraic formula, as long as you use the same unit of measure. Which is one place the metric system does make sense, although I still think in inches and feet.

Hope this makes sense and helps.

Robert

[GregLaROCHE]

Is sight radius the distance between front and rear sights?

[herian67]

Yes

[hawkenhunter50]

Thank you. This is exactly what I was looking for. However, I don’t fully understand the calculation. Where do you account for the distance to target? Also, I don’t know what the 3600 is or how it enters into the equation. Can you give a more detailed example please?
Thanks

Yeah MK42gunner answered it above. For some reason when I copy/paste the info the formatting got out of whack. So the amount of error is 6", sight radius is 19.5" and distance to target is 3600". So 6x19.5=117. 117/3600=.0325 So .0325 is the sight correction needed. Hope that helps.

[GregLaROCHE]

I’m shooting a 405 grain boolit with 66 grains of the equivalent of 2F. Just because it is a paper cartridge, shouldn’t it have the similar trajectory as a 45/70? Does a BP 45/70 cartridge have the same trajectory? When I do the calculation, it says I need to raise the sight 1.38 cm. (.54 inches). That’s more than the current front sight, that has already been raised to correct from 150 to 100 meters.
Does all this make sense?
I did the calculation in metric, then converted everything into inches and yards and the answers, when converted were the same.

[hpbear101]

I have found that a roughly 1/2 high front sight works well for most rifles in the BP era 45-70 class. I make mine from a thin piece of brass fold it over on itself so you have two layers. At the open end pry them apart to form a shallow vee. Solder the two layers together, fit the vee over the existing front sight, when you have a fairly good fit JB Weld (epoxy) the brass sight over the original sight blade. I would start around 3/4" high, file down until you get elevation. You can also file the sides off the brass to adjust windage. If you want to remove the new sight just touch it with a torch and it will come right off.



This is one on a 71 Mauser

Tom

[Mk42gunner]

Bullet weight is irrelevant in this calculation. All this does is tell you how far to move the sight for point of aim to coincide with point of impact, with the same ammo.

With that written, ~½" seems like a lot to move a sight for fifty yards.

What is the sight radius of your rifle? (I looked and couldn't find it, my google-foo isn't working tonight). How far off is the POI? I know you said at least a meter at 50 meters, but a little bit off makes for a miss.

Just for giggles, I did the calculations with a 30"/762mm sight radius (WAG) and got 15.24mm change in front sight height, using one meter as the amount of error. It should look like this: (1,000x762)/50,000=15.24 after converting everything to millimeters as the smallest common denominator.

An easy way to check is to tape/hose clamp/ziptie a piece of wire on the barrel as a temporary front sight.

Good luck,

Robert