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I posted a couple of links in a STICKY about cannon safety shooting rules.

After you look over those rules drop in here tell us what you think.

I noticed one thing right off. Something that I have been aware of for some time. There are different rules for mortars. Properly made mortars should have a powder chamber that is not bore size. How do you determine a safe charge?

I fired off an email to one of the rule posters and asked that question. I'll let you know how they respond.

The other thing about the rules that concerns me is their presentation. Are these safety rules, or are these the correct sequence for firing muzzleloading artillery by the manual of arms as part of a firing competition. The Manual of Arms for firing is interesting but a clear difference, I think, should be made between pure safety and demonstration correctness.

Any comments?
 

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Good links, DD.
I was going to suggest the first one, but had not had contact with the second.

Re: powder chamber. That is, I think, the invention of Coehorn - the officer (general ??) back in the 1600's (?). It allowed more metal around the powder and less was needed later in the burn time when the pressure was lower. My Napoleon cannon has one as well.

How to determine what's a safe charge? I play it very safe by looking at what others are doing and beef it up. As an engineer I know that there are strength formulas and safety factors, but it's not in my area of expertise.
 

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I though about that issue of more metal around the powder. That's why when thinking about making a Mortar tube from an O2 tank I though about making a base plug, threading and pinning it in place. Safety!
 

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Pressure...

Safety should always come first of course! In a bowling ball mortar, only a small amount of powder should be used. With a small amount of BP (and only BP, not smokeless powder!) and the relatively light projectiles that are bowling balls, pressure should not be too high for a high pressure tank.

In a military style mortar, using a heavy ball and up to many pounds of BP, the walls must be thick! And in the old days, the metal used were brittle (cast iron) or not that strong compared to modern steel (bronze, iron, etc). The wall thickness was determined by rule of thumb and following a few century of trials and errors. For field cannons, the wall thickness at the breech around the powder was about the same as the caliber for smoothbores.

In a 24pdr Coehorn mortar using 24 pounds cast iron balls, two 24mm film platic container full of cannon grade powder can launch the projectile a good 100 yards. WIth a half pound of powder, the range is about 1000 yards...
 
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