A fine day out

[Squire Robin]

Started with 18 ounces of shot over 3+ ounces of black as a sort of proofing shot, then dropped it to 9 over 2. It technically failed proof, bit of a blow hole opened up in the iron near the touch, so we stood well back. Movie featuring a mass fly past of geese and only the cannon loaded

http://www.robinhewitt.net/cannon.wmv

Now, how to fill a blow hole so as it can't rust? 

[intoodeep]

Squire Robin,

 Thanks for the post. I enjoyed the video. However, it looks like you had quite the time trying to keep the wheels down....    

[Squire Robin]

  it looks like you had quite the time trying to keep the wheels down....    

It was a bit acrobatic I will grant

Too short a carriage, soft ground and some rather inventive block work for the elevation. I wasn't interfering too much, I preferred to let other people do the loading, target selection, aiming and igniting wherever possible, makes it more fun that way.

[Tropico]

A fun video too be sure. It looks  to be about a 1" bore on that last clip. Myself I use 180 grains in foil and get a big bang with a 3 oz projo .  I would say yours got proofed. Wow ! Is it 41`40 steel or? Personally I thought it was a good looking gun. Perhaps that blow hole can be drilled threaded and filled (a repair).

[Squire Robin]

Good guess, it's 1.35" and I was working to the 2 oz/inch rule. Think I put too much shot in it but you need a lot of shot to get any kind of shot column together. Pea shingle might be a better load.

Don't know what metal it is. It's about 150 years old and cast iron, so whatever iron they happened to use.

Probably good iron because they wouldn't want to slaughter a wealthy customer

[Double D]

Robin,

I think you need to go back an read the Safe loades and cannon plans post.  The 2 ozs. per inch rule is for tubes over 2 inches.  Below is the section on under 2 inch guns.    Your maximum safe load sould have 330 grains.

You projectile weight was a bit excessive  also.  That gun was probably for round ball and round iron ball that size would weight 5 1/3 oz.  Even  round lead ball would have only weighted 8 oz or so.


You definitely proofed that gun. It's a wonder you you didin't break some thing more than the vent.  To fix the vent just drill it out and install a vent liner.


Moderator note: These rules applies only to guns over 2 inch bore. For guns smaller than 2 inch THE MORE COMPLETE CANNONEER compiled Agreeably to the Regulations of the War Department as published in "Artillery Drill" by George Patten, 1861 and Containing Other Observations on Antique Cannon By M.C. Switlik with selected excerts from other artillery manuals Appendix I has a load chart which is posted her by permission of the author.



This load chart is maximum load of a unpatched ball attached to a sabot.

Addendum For mortars and howitzers the the diameter of the powder chamber is the considered the bore diameter.

Click on this link to be taken to the post on loading cannon cartridges

Making Cannon Cartridges

[Squire Robin]

There are many variables to deciding on the charge, but I think I had a bit too much shot because the velocity was very low.

A big factor is the enormous touch hole, 6mm is just shy of 6.35mm which is 1/4", very hard to get the pressure up when your touch hole is oversize.

Another factor is the powder I'm using. Usually I only shoot the finest sporting powder but that's a bit pricy so I'm using a much lower grade, looks like what falls out the bottom of the sieve when they grade quarry powder

Here's a pic of that blow hole, I put a rod in it