Front sight

[dynomike]

Does anyone know why the front sight is so tall? Seems like all them are 3 to 4".

[Double D]

Just a guess on my part, but it probably is because of the extreme difference between the diameter of the cascable and muzzle swell.

My  M-1841 42 PDR has a 4 inch Cascable and 2 5/8 muzzle swell.  The front sight is 5/8 of an inch tall to hit POA at 50 yards...( 1/6 scale equals 300 yards.)  This sight height is also based on using only the the top radius of the cascabel as a rear sight.

[seacoastartillery]

     

Does anyone know why the front sight is so tall? Seems like all them are 3 to 4".

     A little geometry will go a long way in explaining this fundamental truth about field artillery front sights.  Basically, The line of metal, or natural line of sight, is the line joining the highest points of the breech and muzzle, but in some pieces the intervening metal prevents the highest point of the muzzle from being seen when the eye is at the highest point of the breech. In firing, therefore, at what would be point-blank distance, or within that, a muzzle-sight has to be used, the top of which is at a distance above the highest point of the muzzle equal to the difference between the semi -diameter of the muzzle and the semi -diameter of the largest circle of the breech. This difference is called the 'DISPART'.

The natural angle of sight is the angle which the natural line of sight makes with the axis of the piece.

The dispart is therefore the tangent of the natural angle of sight to a radius equal to the distance from the rear of the base-ring to the highest point of the muzzle, measured on a line parallel to the axis of the gun.

     There now, see how just a little bit of elementary geometry explains the need for a typical "gut hook" front sight on most field artillery.  It also explains why Parrott, Armstrong and other artillery designers went to a breech-face and trunnion sight mounting arrangement.

     Note carefully what Double D says above; what he describes is an excellent illustration of our geometric explanation of the effect the Dispart of a piece has on the length of the front sight.

Hope that helps,

Mike and Tracy

[Double D]

I am going to carry it one step further...I am going to file a small notch in the rear reinforce on the cascable of my gun...you see I had the windage on the 500 yard target, I just couldn't pick up elevation reliablity.  Next year!

[Ex 49'er]

Here's a formula for figuring how high to have a front sight:

Subtract the muzzle diameter from the breech diameter then divide by two. You can add a little bit to the height and file it down for zeroing if you'd like. 

[dynomike]

Lets see if i got this right. Breech- muzzle/2=.  8 - 7=1 / 2 = 0.5 or 1/2'

[Double D]

With that sight height you wiil still hit low, but you can use this link to determione correction http://www.brownells.com/.aspx/lid=11181/guntechdetail/Determine_Sight_Height

[subdjoe]

I have to say this - when I see the title of this thead I think of the defensive firearms school.  And that gets me thinking of how you would run the course with a BP cannon. 

Now, isn't the line between the seat for the rear sight and the top of the front sight parallel to the centerline of the bore?

[dynomike]

Now if you add a rear sight you will have to add that distance to, right? I am going to shoot sunday probabely w/o sights. Then i will work on the sights.I was playing around w/ some numbers and here is what i got.

8-7=1/2=0.5
9-7=1/2=1.0 added rear sight if rear sight had a 1" base.

[Cannoneer]

I have to say this - when I see the title of this thead I think of the defensive firearms school.  And that gets me thinking of how you would run the course with a BP cannon. 

Now, isn't the line between the seat for the rear sight and the top of the front sight parallel to the centerline of the bore?

Yes it is. I'm just using these small figures to make it easier (on me, Newton I'm not), so lets say we're talking about a falconet cannon. The diameter of the widest part of the breech (the breech ring) is 4-inches, and the widest diameter of the muzzle (the muzzle swell) is 2-inches. To find out how tall the front sight that I am going to install on the gun should be, (the dispart measurement) so that I can level the gun to fire accurately out to a designated distance (point-blank range), I would take half (semi) the breech diameter, which will be 2-inches, and half the muzzle diameter, which will be 1-inch, and then find the difference between these two measurements, which equals 1-inch; 1-inch is the measure of dispart, and that is the height the front sight has to be. The line that can now be drawn between the top of the breech ring, and the top of the front sight along the line of metal, (a line delineating the exact center of the top of the tube) would be parrallel with the axis of the bore.

[dynomike]

That would put my sight at 1/4".

[RocklockI]

if you choose a Dominck gun BE aware ....those front sights need to be shielded when not being used .

strange but true . they are regular skull punchers .... they are great sights ! my front sight has a corn cob on it just so noone gets a nasty surprise !      REALLY NASTY ..... 

[seacoastartillery]

     I bet if a fellow knew what a file was and had a basic idea of how to use it, he could fashion a copy of an original Parrott front blade sight from a piece of 1/4" cold rolled rod or maybe a a little piece of drill rod and then throw that corncob away.  Just thinkin.  Maybe that could happen......................possibly.

T&M

[carronader]

Not a new discussion...........somebody was taking accuracy very seriously...........Breech looks like Gary

[Victor3]

 That one certainly allows for a generous sight radius and low-mounted sights

[Spuddy]

     

Does anyone know why the front sight is so tall? Seems like all them are 3 to 4".

     A little geometry will go a long way in explaining this fundamental truth about field artillery front sights.  Basically, The line of metal, or natural line of sight, is the line joining the highest points of the breech and muzzle, but in some pieces the intervening metal prevents the highest point of the muzzle from being seen when the eye is at the highest point of the breech. In firing, therefore, at what would be point-blank distance, or within that, a muzzle-sight has to be used, the top of which is at a distance above the highest point of the muzzle equal to the difference between the semi -diameter of the muzzle and the semi -diameter of the largest circle of the breech. This difference is called the 'DISPART'.

The natural angle of sight is the angle which the natural line of sight makes with the axis of the piece.

The dispart is therefore the tangent of the natural angle of sight to a radius equal to the distance from the rear of the base-ring to the highest point of the muzzle, measured on a line parallel to the axis of the gun.

     There now, see how just a little bit of elementary geometry explains the need for a typical "gut hook" front sight on most field artillery.  It also explains why Parrott, Armstrong and other artillery designers went to a breech-face and trunnion sight mounting arrangement.

     Note carefully what Double D says above; what he describes is an excellent illustration of our geometric explanation of the effect the Dispart of a piece has on the length of the front sight.

Hope that helps,

Mike and Tracy

Ummm.....M&T that is an impressive answer.  My father used to answer questions like this with "because".

[dynomike]

Because it's simple.  HA HA The next thing is how are we going to put it on?