Built a replica Coehorn Mortar

[Littlef]

I built a scaled replica of a coehorn mortar, and I just got a chance to go out and fire it. It's scaled to about half size. It can fire a soda can filled with concrete up to about 300 yards. It was a lot of fun to shoot it. The fire restrictions don't allow anything that is set off with a fuse, so I wired it to use model rocket igniters, which is what the wires are for in the video. I put together this little video. Hope you enjoy it.

 

[WestKentucky]

Awesome! I love a good homemade boomer.

 

[Jim Watson]

Could you use a period style friction primer?
I guess a period style linstock would be entirely too sporty.

 

[Littlef]

I looked into that initially, cause I thought it would be pretty neat. Couple problems with that 1. It’s a pretty tight fit to angle it between that base and the barrel. 2. It takes a degree of force to make the friction primer strike. This isn’t very heavy, and the pull would be enough to nudge it off target. 3. I’d have to drill out the hole large to fit a friction primer. It could be done, but then if
I wanted to ever use a fuse, the hole is over sized and the black powder could pour out.

I like the idea of a friction primer, but I just don’t think it’s practical for this particular set up.

 

[Littlef]

Awesome! I love a good homemade boomer.

thanks. It made For a really fun day.

 

[hawg]

That's cool but why such light charges with that heavy of a projectile?

 

[Littlef]

That's cool but why such light charges with that heavy of a projectile?

Thanks! 1. I don't fully trust it. This wasn't proof tested in a lab. It was made in a home shop. 2. I'm trying to safely shoot this, where its going to come down in a safe place, where I can find it, and track its trajectory. I'll bump that charge up more in the future.... but really, bumping up the charge only means I have to walk further to go find the projectile. Shooting it farther isn't really going to make the experience better.

 

[Jim Watson]

Anecdote alert.

“Those guys” had a can mortar with a good deal of windage so range was short. Until they loaded a can with a void in the concrete fill which let it obturate and travel out of sight. The neighbor was alarmed by the incoming.

 

[Shanghai McCoy]

Anecdote alert.

“Those guys” had a can mortar with a good deal of windage so range was short. Until they loaded a can with a void in the concrete fill which let it obturate and travel out of sight. The neighbor was alarmed by the incoming.

So what you're saying is weigh your cans to insure uniform flight results.

 

[doubleh]

A very cool toy.

 

[Littlef]

So what you're saying is weigh your cans to insure uniform flight results.

I think that sounds like a good general rule. I weighed all of mine. I logged all of my powder charges. I bought an anemometer, and tracked wind speed before each shot. I used my GPS and plotted the position of each can and the mortar. Then, I re-verified distance with a range finder. On my next trip out, I plan to make a circle of flags downrange, and try to drop cans in the circle. We shall see. I'm doing this in an effort to understand and better control what is happening, versus just trying to put cans into orbit.

 

[Littlef]

Anecdote alert.

“Those guys” had a can mortar with a good deal of windage so range was short. Until they loaded a can with a void in the concrete fill which let it obturate and travel out of sight. The neighbor was alarmed by the incoming.

The guy who turned my barrel had made this design for several years, and had logged a max distance of 310 yards with a 200grain charge. I started at 1/3 of the max charge. I have an area that goes out beyond 1000 yards. I'm doing this in a safe controlled manner with a clear line of sight. I have no intention of dropping cans anywhere near people or property.

 

[Mk VII]

When they the TV program "The Gun" in the 1970s they used swedes as projectiles. One might last several shots, they found.

 

[Littlef]

When they the TV program "The Gun" in the 1970s they used swedes as projectiles. One might last several shots, they found.

I reading this, and I don't understand what you are trying to say. Is swede the correct word? I don't know what this is. I can't imagine how a projectile is used for several shots, but maybe I'm not reading this right.

 

[Jim Watson]

Swede is another name for rutabaga. A root vegetable apparently dense enough to be used for a cannonball.

 

[Littlef]

Swede is another name for rutabaga. A root vegetable apparently dense enough to be used for a cannonball.

Thanks! That's kinda funny. I know what a rutabaga is. Its dense, but I wouldn't expect it to be intact after being fired from a cannon/mortar.

 

[Mk VII]

Now that I think about it, they were mangelwurzels. It was fortunate that it was market day in Royston, and that mangelwurzels were in season.

 

[Jackrabbit1957]

That would be embarrassing, to have to tell someone you got kilt by a flying vegetable.

 

[Malachi Leviticus Blue]

That would be embarrassing, to have to tell someone you got kilt by a flying vegetable.

Imagine, standing at the pearly gates.
You start by saying "You're never going to believe what just happened!"

Then again it occurs to me that that's exactly what an awful lot of folks would have to say at that moment.

 

[jmorris]

bumping up the charge only means I have to walk further to go find the projectile. Shooting it farther isn't really going to make the experience better.

That’s one reason I never made a powder burner but have launched lots of bowling balls using compressed air. Using a 40 gallon tank and 2” ball valve and a high pressure cylinder.



Do you have details/photos of your build?

 

[Littlef]

That’s one reason I never made a powder burner but have launched lots of bowling balls using compressed air. Using a 40 gallon tank and 2” ball valve and a high pressure cylinder.



Do you have details/photos of your build?

I do have some. I bought the barrel from a guy who made it for me. I do have photos of building the base and inletting the barrel. I can dig those up this evening when I get off work.

 

[hawg]

This guy built a bowling ball mortar out of an oxygen tank. I had six oxygen tanks and 5 acetylene tanks I couldn't get filled. Now I wish I'd kept one. I love the way he measures powder.

 

[Littlef]

yep, I remember finding that video when I was initially researching mortars. That cannon is way cool.

 

[Jackrabbit1957]

Reminds me of punkin chunkin! Or shooting a 45/70.

 

[Littlef]

That’s one reason I never made a powder burner but have launched lots of bowling balls using compressed air. Using a 40 gallon tank and 2” ball valve and a high pressure cylinder.



Do you have details/photos of your build?

Here's a few photos of the build.