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The Mortars we build and shoot.

4K views 8 replies 3 participants last post by  Victor3 
#1 ·
A few weeks ago, Jane I made a 15-day road trip to Easton PA and the annual Victorian Rifleman Gathering. On the way there we stopped at Gettysburg and Lady Jane got a dose of cannon sensory overload.

On the return trip we went through Michigan and enjoyed the “color change” as well as having dinner with two old work colleagues we had not seen in years. My interest in model cannons came up and the subject turned specifically to mortars. After some discussion we came to the conclusion that a bowling ball mortar is not really what could be called a “model” Cannon. I agreed it really could not be called a “desktop” model. We left the dinner with warm memories and the request for me to build them mortars. Their questions were so similar to those questions so often asked and discussed here on the board.

On the trip home I thought about our conversation and decided it might be nice to have a post here detailing the mortars we shoot. This would serve as a good reference for those who come here and are interested in taking up our hobby but don’t know how they want to start.
The SeaCoast boys have their famous “water Jug” Mortar. That mortar is so impressive. Dom has built a number of different designs, his recent “Tank barrel” a real eye opener. It is always exciting to see a Dom post about his latest project, his Dictators always wow. A rumored mortar is that of Rolling block. I have seen a picture and I am most impressed. Rocklock and his casting, Awesome. I know there are others. Who got the GoW Legacy billiard ball and golf ball mortars?

I’ll start with my smallest, and work up. You other guys jump in and tell us about yours. Tell us where you got your mortar or how you built it. Tell us what you shoot and what loads do you use. Big, medium or small post away.
 
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#2 ·
Micro BB Mortar

The smallest mortar I have is a Micro mortar. It very small and was given to me by my next-door neighbor Grand Daughter and my Daughter for Christmas a couple of years ago. I have never fired it. It uses BB’s and micro fuse. I have watched Southpaw fire his. While it is a neat little mortar it just doesn’t get me excited. It is hard to follow to ball in the air and see the impact. Watching the flight and seeing impact is the best part of firing a mortar. I don’t recall what Ernie was using for a load, but distance was about as far as across the room. One caution with these, be careful, steel BB’s bounce all over the room-even with the small charges used. Humm, maybe Ernie wasn’t using a small charge. 😊



These small mortars can be a fun project for a person with a small lathe. These could also be built with a drill press and a file if need be. Small micro fuse, BB’s and Fg powder are all you need to fire
 
#3 ·
Golf ball mortar

This is a common project here on the board. We even had a contest one time to build a golf ball mortar. I have built a number of them around the K.I.S.S. concept that I came up with during the contest. We had four entries. I know GGaskill and Cat Whisperer had entries and maybe Intodeep, don’t remember now, it been a while. Here is my K.I.S.S. Golf ball mortar entry from 2005.



Golf ball mortars for a person that has limited space to shoot, are perfect. Ranges are 30 to 100 yards. If you try to go big and overload and shoot golf balls in low earth orbit you will never see the ball again. This is both boring and dangerous.



The golf ball mortar is good small or medium size lathe project. Simple drilling, boring, tuning project. The hardest part is making the groove for the trunnion. When I drew the plan below for this little mortar, I had in mind to mill the groove for the trunnion. After making the drawing, I came up with the idea to drill a hole through the stock before turning the radius profile. When the radius is turned it will result in an interrupted cut. Go small and light as you cut.



I made this drawing while taking a CAD class at college. Later we printed it out on a 3D printer.



Powder charges are conservative, the K.I.S.S. mortar using 20 to 25 grains for a normal loading ranged out to about 30 yards. Increased loads will get more range. But because of its light weight, as you increase charge weight, recoil becomes a factor with the K.I.S.S. mortar. Too heavy a load and the mortar will go flying across the ground.

You aren’t limited to shooting golf balls. Gary-Rocklock arranged for a grinding ball company to make a run of 1.68 diameter steel grinding balls for us at one time. That company sold out and would not make another run. There are still some around if you keep you eye open. Rotometals also has zinc round balls in several sizes including These work quite well and can be used over and over. But with lighter weight mortars recoil can be a factor with steel or zinc balls. Light loads are called for in the smaller lighter guns.

I had Gary-Rocklock cast me a bronze barrel and Michael-Zulu cut me out the base and I finish it out and built a beautiful golf ball Coehorn. I never fired this one. I gave it to a friend as a thank you for looking out for me after Katherine died.

Here is a complete album of photo’s including plans that I used to build this mortar.

[url="http://www.fototime.com/inv/0BD7113B36F79E2"]Golf ball coehorn01



The golf ball mortars are small, compact and fun. They can be carried in one hand and are easy load, shoot and clean. Over the years since I built my first gun, my gun has evolved.



While looking for picture to illustrate this post I found this old video that I could not resist posting. Click on the picture to play.

 
#4 · (Edited)
Pop-can mortars

The pop can mortars are about as big as you want to get and still have “one-man” operation. You can shoot these on a small lot, but you won’t want too. Jane and I have two of Dom’s Dictator for popcan shooting.



I have a large Dictator, Dom built me a while back. It is a beautiful big, heavy gun. It weighs just over 90 lbs. It can be crewed by one person, but it is much easier set up with two people.



Jane’s Dictator is one of Dom’s kit mortars and is one of best deals to come along in a long while. It weighs in around 60 lbs. It is a shame he doesn’t still make this one.



The mortar and especially the popcan mortars are easy to load and shoot. They have good range and good visibility when shot. Cement filled pop cans are good for the basic load, but round balls are just more fun. Here is a link to a load test of this gun. Lady Jane builds a Dictator

I did build a K.I.S.S pop can mortar, and it came out quite well. It is a good solid platform. Simple to build and not overweight and cumbersome.



My build post on that mortar can be found here https://www.go2gbo.com/forums/88-bl...er-2010-2011-projects-k-i-s-s-can-mortar.html.

The K.I.S.S. pattern mortars are good basic mortars for a first-time cannon project for a home shop to give a person some ideas about how a mortar is constructed. It is isn’t a pretty mortar, just a good beginner’s mortar. Build one of these for a first project and you will want to build another nicer.

As a subset to the popcan mortars, I have is a 6 PDR mortar tube. I got this tube in trade. It is made of 4140. It originally had a popcan bore-slip fit. It had no windage and was just too tight to use as mortar. If you put a popcan in the bore it would slowly side down to the bottom. I had Wes Pilley-PowderKeg open it up for me all the way to 3.67 inches, 6PDR. Right now, it is just a cylinder with a hole in it. The back needs profiled. Southpaw fabricated a band and trunnion affair for me. I scabbed some old beams together and made it up into shooting mortar that I call the Junkyard Dog. I am looking around for a machine shop to turn the radius for me. I want to build this out to replicate a Confederate 6PDR Coehorn.



Zinc balls for the popcan and 6 PDR are available from Roto Metal . Zinc balls are a bit expensive, but recoverable and reshootable.
 
#5 · (Edited)
Bowling Ball Mortar

Sooner or later in this hobby you will be exposed to bowling ball mortars. Every time in the early days of this hobby when I saw one fired, my reaction was “Wow, I gotta have one of those”. The reality of it was, I don’t have a deep enough pocket to buy one. or the right shop-tools to build one. But, I could dream. I saw all kinds of them. After a while I noticed a number of them built on some sort of pressure bottle. Most were unappealing and unimaginative to me. Cut off the end of the pressure bottle and add some legs for a sort of look like Stokes mortar. Stokes of course being an early 20th century design and didn’t really fit the theme of this board, and for a while were not allowed here. After a while, we relented and allowed the Stokes here, as long as it used an antique ignition system.

We have had a number of bowling ball mortar builds posted over the years. I just used the Google Search code to find posts on old GBO about Bowling ball mortars. Copy that line below and paste it the Google search window.

Code:
site:www.go2gbo.com/forums bowling ball mortar
While I only got just over 400 hits on Google I was surprised that the earliest discussion was in February 2003. We only started this board in 2002. I was right in the middle of that discussion, showing desire, dealing with reality of building a bowling ball mortars and concluding it being beyond my means. Here is an early bowling ball mortar post by W. A. Tyrell and his mortar. Later we had another fellow build a bowling ball mortar with a pressure bottle that looked like the 10-inch Seacoast mortar. I tried to find a link to that build as it very well done. Former Marine if I remember right.

Building a bowling ball mortar is big undertaking. Designing is pretty simple. Building is actually pretty simple if you have or can get access larger tools. A bigger lathe, mill and drill are needed for this project.

The greater problem is logistics. How do you move it?

A Stokes style is fairly simple and for the most part a one-man operation. Small size helps a guy get into the game as long as he sticks with small charges. Larger charges require heavier guns to control the effect of recoil. Nothing scarier than to have a cannon or mortar to go flying in recoil. The ball has departed barrel before recoil, I think? I hope, hasn’t it?

How do you move a gun that weighs 800 lbs., that is the greater problem? I built a wheeled carriage so I can l move my gun around. I have to have a trailer or pick-up truck to move it to the field. That is of course when I can find a field where it can shoot.



Then there are powder charges themselves. My K.I.S.S. bowling ball mortar lobs a 15-pound ball 400 yards with 6 ounces of powder- 2-2/3 shots per shoot per can. I don’t shoot this every weekend.

Finding a correctly built bowling ball mortar to buy can be tough. There is one available commercially, but there also exists video of its square tube frame folding up and its tube bulging and powder chamber cracking—although the mortar was abused by shooting smokeless powder instead of black.

Even though I had pretty given up the idea, over the years I still kept my eye open for a pressure bottle. During one of the Cannon conventions in Montana, while sitting around in my back yard talking cannons the conversation turned bowling ball mortars. I mean the SeaCoast boys brought their giant mortar that shot water bottles, where else could the converstion go. I don’t remember all the discussion, but it wasn’t long after that event after that George, GGaskill emailed about a piece of 8 ½” ID tube steel. It was all downhill from there, ending with an attempt to fire a bowling ball a mile. The attempt failed as the ball got lost in the tall grass 2 miles down range.



Here is a link to my build. K.I.S.S. Bowling ball mortar. Lots detail in there.

I built my bowling ball mortar on a budget over a period of about 10 years. In one year, I doubt I spent over $300 total on the project, except for the wheels. In 2009 George found me the barrel steel. In 2011, Dom helped me acquire the base plug. George helped me acquire another piece of steel for the trunnion shortly after that. (actually a second piece for a trunnion after a redesign) 2012 was the wood acquiring year. Finding suitable wood was the most difficult acquisition. The single most expensive purchase, the wheels came at the end of 2012. In 2013 I went to Afghanistan. While overseas I had a local farmer do the barrel machining. When I returned from Afghanistan, my lifestyle was changed, and I was travelling back and forth between Montana and Oklahoma. When in Montana in 2014 and 15 I used my contacts to get access to machines to do heavy drilling and milling. I had a false start on the wood, so I had to buy more wood from a custom resaw mill before I left for overseas. I carried this wood back and forth between Montana and Oklahoma a couple times for tool access. I had a drill press in Montana but for convenience sake I bought a second drill press in Oklahoma. Mounting hardware was built from bits and pieces I scrounged or ordered from Speedy Metals or bought over the counter at Metal express. I did the small drill, saw and lathe work on the hardware. I subbed the welding out to local kid looking to make a few bucks on the side. I fired the first shoot May of 2015, about 7 years from first really serious brainstorm to smoke and fire. I still have some small parts to fabricate on this gun before I can call it finished.

 
#6 · (Edited by Moderator)
That is quite a collection mortars. And all that open country to shoot them in I am envious. I only have one mortar, a 3 inch. The tube came from Jack Hern, the hardware and base were built by me from local sources. The base wood is rustic hickory and it's name is ol' Hickory.
 

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#7 ·
:tango_face_grin:Nice looking mortar. I turned the images for you.

The cast iron barrels are a bit rough when they come. What did you do if anything to clean that up and finish that out. What does the finished gun weigh?

Have you fired it yet? I think you have been around long enough to know we are never satisfied until we see smoke and fire pictures.:tango_face_grin: Even then we still want more.
 
#8 ·
There are some vids in another post but I'll try adding one. The barrel was pretty smooth on the outside I just sanded it some with my palm sander and 80 grit to get the black rust coating off then moved up to 150 grit and painted it. There was a couple small pits I didn't like so I filled them with a dab of JB weld and filed it down. The bore still had casting sand stuck to it. I cleaned it up the best I could then honed it with an automotive cylinder hone and plenty of oil. It came out great.
 
#9 ·
I haven't fired any of my mortars in years. One of my favorites, a BNA cork mortar, sits on a shelf among other small militaria items. And sadly...

"After 10 years of successful production the manufacture of new cork mortars is being spun down. As of late 2019 no further cork mortars are being crafted or sold."

https://bircherinc.com/bna-cannons/
 
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