Barrel length and powder chamber dimensions?

[Al Bently]

I am doing the layout for a BP muzzleloading cannon or mortar (haven't decided which yet) I hope to build and I have a question about barrel length and powder chamber dimensions?

The nominal OD of the projectile will be 2.50" and it will not be patched in any way. The nominal ID of the barrel will be about 2.75" Plenty of "windage." The piece will be charged with between 50 and 500g of F BP.

Given the fairly loose clearances will barrel length still make a big difference? I have a fairly wide latitude of how long I can make the barrel and I'm curious how big of a difference a barrel say twice the length of another will make in this application?

I'm also curious about powder chamber sizing. I have seen diameters for pieces of this sizing ranging in diameter from 1 to 1 5/8" and from 1 to 1.75" in depth. Any insight to how differing dimensions affect performance would be appreciated. Thanks.

 

[coloradoclyde]

The piece will be charged with between 50 and 500g of F BP.

:shocked2: UMMMM I hope your not talking grams.....500 grams is over a pound of powder :nono:

What do you want on your tombstone?

If your talking grains your still going to have some problems.

 

[Poor Private]

Why should he have a problem at 500 grains? Thats only a bit over 1 oz. I fire 1 oz regularly out of my 1" swivel, with a 24" barrel(of course that is a blank load). If your live firing start at 1/4 oz and work up. And a cannon doesn't need a chamber, it's just a tube. I make 1/2 to 1 oz cartridges out of aluminum foil. I use a postal scale and powder measure to fill my cartridges. And if your making a big enough tube go to Dixie and buy the slap hammer and install, instead of using fuses. In my opinion it's much safer.

 

[robert reed]

I copied this chart from a book years ago. I don't remember which but it was 19th century IIRC.

My home made cannon has a 2" bore and a 1x3" chamber bored into the 2x6.25" breech plug. It is pressed, pinned and welded. I have fired blanks up to 500 grains, fairly shakes the earth but my guns breech can be held in the hand an there is no movement, even when firing projectiles. Maybe I over built it some. Modern steel is so superior to the castings used in the past that using old charge charts is a very safe bet.

 

[coloradoclyde]

Why should he have a problem at 500 grains? Thats only a bit over 1 oz. I fire 1 oz regularly out of my 1" swivel, with a 24" barrel(of course that is a blank load). If your live firing start at 1/4 oz and work up. And a cannon doesn't need a chamber, it's just a tube. I make 1/2 to 1 oz cartridges out of aluminum foil. I use a postal scale and powder measure to fill my cartridges. And if your making a big enough tube go to Dixie and buy the slap hammer and install, instead of using fuses. In my opinion it's much safer.

A 2.75 " barrel and a 50 grain charge in a cannon and you run the risk of the powder charge sliding under the projectile causing a misfire....
I use a powder scoop on the end of a broom handle to precisely place the powder charge..
Never used a cannon lock but a fuse with a light charge can be problematic.

Just don't want to see anyone get hurt.

 

[Al Bently]

Why should he have a problem at 500 grains? Thats only a bit over 1 oz. I fire 1 oz regularly out of my 1" swivel, with a 24" barrel(of course that is a blank load). If your live firing start at 1/4 oz and work up. And a cannon doesn't need a chamber, it's just a tube. I make 1/2 to 1 oz cartridges out of aluminum foil. I use a postal scale and powder measure to fill my cartridges. And if your making a big enough tube go to Dixie and buy the slap hammer and install, instead of using fuses. In my opinion it's much safer.

Actually a cannon is more than "just a tube." The powder chamber is a hog-out with a much thicker wall thickness than the barrel itself, thus it's far stronger. It also aids touching-off the load by physically concentrating the powder in a smaller area.

You're right about the 500g not being an issue. It's not even close to being an issue. The piece will be easily capable to safely shooting 2 ounces of F BP.

 

[coloradoclyde]

Actually a cannon is more than "just a tube." The powder chamber is a hog-out with a much thicker wall thickness than the barrel itself

True....on cast barrels. Are you casting a barrel?

Most homemade cannons that I have seen are made from seamless tubing...

I wish you the best of luck in your endeavor and look forward to your progress. :v

 

[Joel/Calgary]

CClyde was responding to CalGunner's use of "g" as the abbreviation for his powder charge units. "G" is properly the unit designation for grams, while "gr." (preferably with the period, as an abbreviation) is the proper unit designation for grains. A lot of us live with both units and the differentiation is important, by a factor of 15fold. In context, it was probable but not certain that he intended grains, but that ain't what he wrote.

Regards,
Joel

 

[Al Bently]

CClyde was responding to CalGunner's use of "g" as the abbreviation for his powder charge units. "G" is properly the unit designation for grams, while "gr." (preferably with the period, as an abbreviation) is the proper unit designation for grains. A lot of us live with both units and the differentiation is important, by a factor of 15fold. In context, it was probable but not certain that he intended grains, but that ain't what he wrote.

Regards,
Joel

Like it or not, in the context of BP marksmanship, "grains" is often (and correctly) abbreviated as "G" or "g." That's indeed what I wrote.

 

[nightwolf1974]

Why should he have a problem at 500 grains? Thats only a bit over 1 oz. I fire 1 oz regularly out of my 1" swivel, with a 24" barrel(of course that is a blank load). If your live firing start at 1/4 oz and work up. And a cannon doesn't need a chamber, it's just a tube. I make 1/2 to 1 oz cartridges out of aluminum foil. I use a postal scale and powder measure to fill my cartridges. And if your making a big enough tube go to Dixie and buy the slap hammer and install, instead of using fuses. In my opinion it's much safer.

in my small homemade cannons (under 1") I use 150 grains of 2F and slightly smaller PRB...or TP wads, and some sand.

in the bigger homemade ones (1.25" and upto 2.25") I use 350 grains of 2F,TP, & shot or sand.

don't know what i'll use when I make one with a soda can size bore.....to shoot Coke cans full of cement.

I also light a fuse and run.

 

[satx78247]

Would you gentlemen, who know a great deal more than I do about the BIG GUNS, care to give me an idea on the proper load of powder & shot for a 60mm bore punt gun, with a barrel about 7 feet long with 18mm barrel walls??
(The barrel will be made of a piece of spiral welded, inside & out, oil-field HIGH PRESSURE tubing, which is about 2.3 inches ID.)

All of the resources that I have, including the "original data" from the Smithsonian's exhibit on "punt guns", is both inexact & confusing.
(For example, one of the 2" bore guns, THE BROWNING, was said to use 4 hands full of black powder & 4 hands full of shot. = How much is THAT in ounces?? - Chuckle.)

THE WALKER, which was FIVE INCH bore was said to use, "Four measures of powder & an equal weight of shot".
(How much is a "measure"??)

yours, satx

 

[steam1993]

I use 1.5 to 2 ounces of BP in my 1.25 in bore cannon with a 6oz lead shot. Ball will go nearly 1 mile.

In my mortar I use about 1 ounce of BP the ball which weighs 24 pounds goes 100 yards, with a 8 ounce charge the ball will go appox 1/2 mile

peter

 

[nightwolf1974]

**** in my small homemade cannons (under 1") I use 150 grains of 2F and slightly smaller PRB...or TP wads, and some sand.

in the bigger homemade ones (1.25" and upto 2.25") I use 350 grains of 2F,TP, & shot or sand.

don't know what i'll use when I make one with a soda can size bore.....to shoot Coke cans full of cement.

I also light a fuse and run.****

I work up a load for the barrels by making 2 prototypes of each kind. I clamp one down on a 70lb base I made that sits behind an earthen backstop, then load it and point it in a safe direction, then light the fuse and run. IF the barrel doesn't burst(never had one do it yet) and looks solid after a good inspection, i'll fire it a few more times and mount it on a carriage. I know that mine aren't fired at full potential, but I'm happy with the results.

 

[satx78247]

How much shot do you use in your 2.25" bore cannons with 350 grains of BP??
(60MM is NOT that much bigger than 2.25".= 60mm is about 2.36 inches.)

yours, satx

 

[nightwolf1974]

How much shot do you use in your 2.25" bore cannons with 350 grains of BP??
(60MM is NOT that much bigger than 2.25".= 60mm is about 2.36 inches.)

yours, satx

last time I did (12-21-12) I shot 2oz of daisy BBs.

 

[satx78247]

THANKS. = That gives me a "starting point", though I'm not terribly worried about rupturing the barrel, inasmuch as that VERY expensive piece of oilfield tubing is individually x-rayed & tested by other more extensive means by a certified lab for FAR more pressure than any reasonable amount of BP can generate.
(The piece of tubing was given to me, by the tool-pusher/rig boss on one of the rigs on our family's farm, as "scrap", as it was a mis-measured "cut-off", that's a little less than 8 feet in length.)

I suspect that THE TRIX-LIZ will "speak with great authority" & a mighty roar.
(Btw, ALL punt-guns originally had "a name" by which they were referred to.)
Often the BigGun's "name" was the family surname of the original owners. - I also know of two punt-guns that were named after the owner's mother or wife. = THE EMILY ANNE & THE ROSE MAE.
(I also know of a punt-gun that was named after a well-known, "talkative" & rather LARGE lady from Easton, MD = THE BIG-MOUTH ALICE ====> I doubt that the lady was pleased/flattered!! - CHUCKLE)

yours, satx

 

[nightwolf1974]

THANKS. = That gives me a "starting point", though I'm not terribly worried about rupturing the barrel, inasmuch as that VERY expensive piece of oilfield tubing is individually x-rayed & tested by other more extensive means by a certified lab for FAR more pressure than any reasonable amount of BP can generate.
(The piece of tubing was given to me, by the tool-pusher/rig boss on one of the rigs on our family's farm, as "scrap", as it was a mis-measured "cut-off", that's a little less than 8 feet in length.)

I suspect that THE TRIX-LIZ will "speak with great authority" & a mighty roar.
(Btw, ALL punt-guns originally had "a name" by which they were referred to.)
Often the BigGun's "name" was the family surname of the original owners. - I also know of two punt-guns that were named after the owner's mother or wife. = THE EMILY ANNE & THE ROSE MAE.
(I also know of a punt-gun that was named after a well-known, "talkative" & rather LARGE lady from Easton, MD = THE BIG-MOUTH ALICE ====> I doubt that the lady was pleased/flattered!! - CHUCKLE)

yours, satx

make sure you post pics when it's done. i'll post pics of my 3" and 3.5" cannons when they are done too. I like to use thick walled bushing material for my barrels and pin stock for my plugs. I can weld good, but my father who's done it for 50+ years do them....that ways there's no question on the weld.

 

[satx78247]

WILCO.

THE TRIX-LIZ will NOT be completed in the USA.- I'm planning to build the barrel but NOT install the Brown Bess lock & trigger mechanism until I'm "way down South".
(IF the gun is "assembled" before being imported it must be registered as a "shotgun of greater than 10 gauge" & "go through customs". - The barrel & mount can be imported, if unassembled, without any "paperwork" whatever. - When assembled there, it is NOT even considered to be a "firearm" as flintlocks are completely UNREGULATED.)

Also the gunning-punt that will carry the Big-Gun will be built in Latin America, once I get retired/settled down there for 2 reasons:
1. Transporting a 6x1M boat would be needlessly expensive
and
2. The wood that is available there is both cheaper & better quality in those lengths than it is here.
(Piranha Pine is, believe it or not, used to make PALLETS down there. - You wouldn't want to know what that much Piranha would cost here.)

Note: The gunning-punt will be built of full-length 12x30mm strips of Honduras Mahogany over hardwood frames on 400mm centers & "stuck-together" with epoxy "peanut-butter" & then "armored" with glass cloth & more epoxy.
The mast will be made of a 400MM length of clear hardwood to mount a gaff sail & will have a pair of dagger-board to assure that it tracks straight.
(The original gunning-skiff, that I'm going to copy, was said in period documents to be "swift under sail".)

yours, satx