Author Topic: Hern's Coehorn Mortar (Read 1263 times)

Evil Dog · « **on:** April 07, 2005, 02:57:27 PM »

I'm starting to very seriously look at the Coehorn Mortar from Hern Iron Works. A 14" tube weighing around 80 pounds with a 2 1/4" bore. It does NOT however have a powder subchamber.... rather it is a straight 2 1/4" bore all the way to the flat bottom. I'm wondering just how important the powder subchamber is. Without the subchamber would this be more accurately described as a really short barreled howitzer that is fired at an extreme elevation?

I really do like their half scale Napoleon.... the Coehorn is the same bore size so will only have to cast one size ball.

http://www.hernironworks.com/cannons.html

Cat Whisperer · « **Reply #1 on:** April 07, 2005, 03:57:18 PM »

When you see 'sold for decorative purposes only' and 'no warrenty' you're on your own. The meaning is obvious.

threepdr · « **Reply #2 on:** April 11, 2005, 04:37:06 AM »

It would not even be a short barreled howitzer. Howitzers were chambered also. I've seen several of these fired and they look fun. The draw back of not having a chamber is the inability to get a consistant range and accuracy especially with small charges. The chamber solves that problem.

Having said that I've seen hundreds of Hern tubes used in Civil War and Rev War reenactments for almost 30 yeas of my living history hobby. They are not as pretty, or as well finished as more expensive guns, but I have never heard any safety issues with them. For live fire with their long barreled guns, there is the potential to have problems live firing due to off axis liners. I've heard of some that shoot straight, others not so straight.

One of the Rev War units I work with has one of the Hern Carronade tubes (with is a mis-nomer since it is not really a carronade) that sat out side of a fellows house in the rain for over ten years on a fake carriage. They bought it, drilled the vent, clean and painted it and I think they used a brake hone or something to smooth up the bore. They have fired thousands of blanks out of it with no issues.

CU_Cannon · « **Reply #3 on:** April 11, 2005, 04:57:10 AM »

I'm wondering if it would be possible to bore it out and sleeve it. A breach plug could be made with a powder chamber. You would need a significant lathe or a milling machine with a boring head to accomplish the boring. If you were to go through that much effort you might as well build one from scratch. It may be cheaper and almost quicker from what I've heard about whats needed to finish the casting.

CrufflerSteve · « **Reply #4 on:** April 12, 2005, 04:45:17 PM »

I don't know if a reduced chamber is all that necessary for the 2 1/4" Hern uses for bore. In the "More Complete Cannoneer" the author of the modern part discusses 'subcalibering' in repro cannon and seemed somewhat in favor of the idea.

The old mortars and howitzers typically fired hollow exploding iron rounds. That would make them pretty darned light compared to a solid casting. I'm hoping to try my hand at zinc casting this summer. From postings on this list, getting good quality solid castings of zinc can be a challenge. Imagine the fun of casting hollow shot! Imagine the even greater fun if it made people think we were going to fill it with something that goes bang.

Hern isn't the only maker of repros that I've seen doing the subcalibering approach.

Steve