Aiming a mortar

[Scota4570]

I shot my mortar again last weekend. The wind was only about 5 mph., last week it was about 40 mph. this time accuracy amazed me. I dropped several cans within 10-feet of my target at 200 yards.

I was only sighting down the edge of the base. I would like to do better. I would like to avoid gettin on my belly, there are burrs and thissels at my shooting spot. Anyone have ideas, plans or pictures of sights I could make? I do not care that the sight would be illegal in competition.

 

[Bob Riegl]

:hmm: Well after considerable thought on this question. I thought back on my Artillery days in my Uncle's service. I would take two small 2"X2" rare earth magnets and embed them in the base so that they are in line with the bore of the mortar---now using a piece of sheet iron bend the iron into a long , low height "u" now you could make a sight in any style you wished out of this piece and then just lay it on the magnets. The magnets hold the sight in place and you can remove it when the (idiots) PC police arrive. You could also make this into a "Gunner's Quadrant" by modifying the simple sight with an additional compass type device that would measure the angle of the tube as well. The only reason I haven't gotten into mortars is that there is no legal place on L.I. to shoot the durned thing. :v

 

[4sd4d]

the best suggestion I have is fairly complicated.

It involves physics and trigonometry.

but if you find out how much force a known volume of powder provides, the firing angle of the gun, and the weight of the projectile, the shots should be faily consistent given an immobile base.

 

[Scota4570]

Hmmm, not what I am after. I need a way to point the tube in a precise manner. If it had real sights I could use them to got on target very fast. Just for arguments sake say we put a scope on it. I fire one shot and make not of where the can lands. I can line up my scope and gun on the old aiming point. I not move only the scope to where the can landed. I can them adjust the powder charge for distance. I shoul be on of windage on a shot or two.

 

[Scota4570]

Sorry that post was a mess. Lets try again.

I need a way to point the tube in a precise manner. If it had real sights I could use them to got on target very fast. Just for arguments sake say we put a scope on it. I fire one shot and make note of where the can lands. I can line up my scope and gun on the old aiming point. I now move only the scope to where the can landed. I can them adjust the powder charge for distance. I should be on for windage on a shot or two.

What I am thinking of is a sort of windage adjustable sight. The front sight would consist of a stretched vertical wire in a frame. The rear sight would be a vertical slot or a peep. The eyepiece would run side to side on a track or two 1/4" steel rods. The movement would be controlled by a piece of all-thread and a thumbwheel. It would basically be like a real peep sight or a little lathe bed with a lead screw. A mirror could be used to make it easier to look down on the sight rather than get on your belly to use the sight.

 

[Bob Riegl]

:v Sounds to me like a darned good idea---start putting it on paper, build a model, try it, make any adjustments and build the final. The use of some kind of mirror would possibly preclude the need to get down on your belly for sighting. Are there any artillery re-enactors in your are---or check with NSSA for more information. :thumbsup:

 

[TheDoubleD]

First get two stakes about 3 feet high. Drive them in the ground. One in front of your firing position and one behind your firing position, aligned so they are pointing from your firing position to your target. Stretch a heavy white string between the two stakes. Step back behind your firing position and look down the string. The line of the string should pass through your firing postion and to the target.

If your vent is TDC drill a hole TDC in the muzzle ring. If your vent isn't TDC drill a second TDC hole near the rear of the your tube Make a sighting string and two pins.Put the pins in the TDC holes and stretch the sighting string between the two pins.

Align the mortar under the stake string so the sight string on the mortar tube is aligned with the stake string. Drop the stake string, pull the sight string and fire.

I saw a mortar that when made had a line scribed TDC the length of the tube. The crew then wiped a piece of chalk in this groove. This of course in liey of a sighting string

I saw several variations of this at Fort Shenandoah with Mortar teams using sighting stakes and string sighting down the edge of tubes and bases as well.

But most on them seem to just be eyeballing it

 

[Scota4570]

Very interesting, how do you align the vent and muzzle pin on the string if your tube is not able to go below 45-degrees? Mine rotates up to vertical for loading and down to 45 or so for firing.

 

[Scota4570]

Very interesting, how do you align the vent and muzzle pin on the string if your tube is not able to go below 45-degrees? Mine rotates up to vertical for loading and down to 45 or so for firing.

 

[4sd4d]

it sounds like you have a pretty good idea of what to make.

Shouldn,t need to be too precise though, the thing with mortars is just to get close, shrapnel takes care of the rest :thumbsup:

 

[TheDoubleD]

The method described is for adjusting windage. The sighting string or line on the tube aligns with the aiming stakes line. Just stand back behind the mortar and look at the two stings and line them up. The sight stakes point at the target, aligning the mortar under the string points the mortar in the same direction

For a elevation-distance you increase or decrease powder charge.

Coehorns tubes are fixed and not elevation adjustable.

Some older Seacoast mortard did have some elevation adjustment, but not much.

 

[Bob Riegl]

:v Shoulda thought some more and remembered the old battery aiming stakes and the surveying crew. I may know something about pre- 1970's artillery but never learned about using the coehorn, that's for sure. I was the BC in the FA and really had little to do with unit set-up, the first three-graders did it all thankfully. I would love to learn more about the coehorn, but the nearest re-enactor Battery is about 200 miles away---too much driving with gas now at $3.05/ gallon. I will google Coehorn and see what I can learn. :thumbsup:

 

[GunneyG]

What you need is a really high rise scope mount. Assuming you have a block mount Coehorn, I would make two rods that fit tightly into the notches front and rear. To these, I would weld two equal length uprights such that they come together above the barrel. Then I would weld them to a piece of 1" square tubing the goes between them. Finally I would weld a couple of pieces down low to keep the end pieces at a fixed distance. Drill and tap the square tubing for a Weaver type base and mount your scope. Highly non-prototypical but it should work. If the description is confusing, I can make a drawing and post it.

 

[smoothshooter]

What does "TDC" mean?-Smoothshooter

 

[TheDoubleD]

TDC= Top Dead Center