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-   -   Buddy of mine wants to build a cannon (http://www.firearmstalk.com/forums/f22/buddy-mine-wants-build-cannon-62790/)

Scratchammo 04-18-2012 04:58 PM

Buddy of mine wants to build a cannon
 
So a buddy of mine wants to build a black powder cannon with 4130 chromoly cold rolled steel tubing measured at 18" long, 1" in caliber, & a 1/4" wall. He said he wants to replicate loads similar to that of a swivel gun but he said he's not stupid enough to hold it. He wants to use a solid round ball & ffg pyrodex. How many grains should can that tube handle safely?

hiwall 04-18-2012 08:33 PM

How are you plugging the end of the tube? That is the area of most concern. Cannon builders frown on welded on ends.

Ranger-6 04-18-2012 08:42 PM

Your friend might want to check FFL regulation.

purehavoc 04-18-2012 10:33 PM

Out of personal experience I dont think 1/4" wall thickness it heavy enough for that kind of load shooting a projectile .
My uncle has one he build its more like 3/8" thickness about 18" long , we load it up jab newpaper in it and pack that ol girl tight with a 1" oak dowel and rubber mallet , stand back 20 or so ft and pull the drop cord . KAAAAABBBOOOOMMMMM it has 3 legs about 8" long with 2" flat circle bases . you should see what it does to a truck bed when it goes off back there . 3 real nice perfect circles about 1/8" deep . We make sure its on the ground when it goes off now :)

Scratchammo 04-18-2012 11:03 PM

Quote:

Originally Posted by hiwall (Post 774852)
How are you plugging the end of the tube? That is the area of most concern. Cannon builders frown on welded on ends.

He's gonna have it threaded for a 1" screw plug.

Scratchammo 04-18-2012 11:07 PM

Quote:

Originally Posted by Ranger-6 (Post 774856)
Your friend might want to check FFL regulation.

I looked around & couldn't find any FFL regs for cannons using black powder.

c3shooter 04-18-2012 11:23 PM

4130 is a decent material- it is used for modern rifle barrels.

As indicated, the issue is not so much the material itself, but how the breechplug will be held in place- and welding is not generally a good idea. Also, consider how the trunnions are attached- you do not want to be changing the heat treatment of the steel.

If it uses loose powder and ball, and does not use modern primers, ATF does not care- it is not a firearm (it is an antique- even if you made it today)

The load will not be as critical as you might think- what does not get burned in a black powder barrel gets blown out as unburned powder. So long as you use black powder (or a BP substitute) and the projectile is FIRMLY AGAINST THE CHARGE- it would be hard to burst a barrel.

I made one cannon as a present for a friend (hey, he bought a boat- needed something to repel pirates, OK?) THAT one started as a 3 inch rod of bronze, 4 inch length over chamber left full sized, then tapered down to 1.5 inch OD barrel, smooth bored to 0.75 inches.

Proof fired that with 200 grains of ffG, and a 1 oz lead slug. Had touchhole, used cannon fuse (a LONG length of fuse!) 4 proof shots, no changes in exterior dimensions. He mainly uses it as signal gun, 75 gr ffG, paper wadding.

BTW, these folks are firing BOWLING BALLS using cut off oxygen tanks. Those are made out of (I think) 30 CrMo, have a wall thickness about 5.7-6mm.


Scratchammo 04-18-2012 11:26 PM

Quote:

Originally Posted by purehavoc (Post 774972)
Out of personal experience I dont think 1/4" wall thickness it heavy enough for that kind of load shooting a projectile .
My uncle has one he build its more like 3/8" thickness about 18" long , we load it up jab newpaper in it and pack that ol girl tight with a 1" oak dowel and rubber mallet , stand back 20 or so ft and pull the drop cord . KAAAAABBBOOOOMMMMM it has 3 legs about 8" long with 2" flat circle bases . you should see what it does to a truck bed when it goes off back there . 3 real nice perfect circles about 1/8" deep . We make sure its on the ground when it goes off now :)

Noted. I guess we'll have to start with small charges & measure for chamber expansion along the way.

Scratchammo 04-18-2012 11:44 PM

Quote:

Originally Posted by c3shooter (Post 775033)
4130 is a decent material- it is used for modern rifle barrels.

As indicated, the issue is not so much the material itself, but how the breechplug will be held in place- and welding is not generally a good idea. Also, consider how the trunnions are attached- you do not want to be changing the heat treatment of the steel.

If it uses loose powder and ball, and does not use modern primers, ATF does not care- it is not a firearm (it is an antique- even if you made it today)

The load will not be as critical as you might think- what does not get burned in a black powder barrel gets blown out as unburned powder. So long as you use black powder (or a BP substitute) and the projectile is FIRMLY AGAINST THE CHARGE- it would be hard to burst a barrel.

I made one cannon as a present for a friend (hey, he bought a boat- needed something to repel pirates, OK?) THAT one started as a 3 inch rod of bronze, 4 inch length over chamber left full sized, then tapered down to 1.5 inch OD barrel, smooth bored to 0.75 inches.

Proof fired that with 200 grains of ffG, and a 1 oz lead slug. Had touchhole, used cannon fuse (a LONG length of fuse!) 4 proof shots, no changes in exterior dimensions. He mainly uses it as signal gun, 75 gr ffG, paper wadding.

BTW, these folks are firing BOWLING BALLS using cut off oxygen tanks. Those are made out of (I think) 30 CrMo, have a wall thickness about 5.7-6mm.

http://www.youtube.com/watch?v=dIMNdobqUH8

HOLY CRAP!!! I need that :eek:

Yep, it'll be loose powder & ball (or other stuff). I talked him out of welding a plug. I'll have to post videos of this thing once it's completed.

W. C. Quantrill 07-07-2012 09:37 PM

There are numerous articles on building and firing cannons on the searches. The rule of thumb on cast cannons was that the barrel was as thick as the bore. Everything about a cannon is in relationship to the bore diameter. Even the wheels are functions of bore diameter. There are also some books available that give specs on the cannons.

I suggest that you all get into a bunch more research before you do this. The info is online.

The amount of powder is also a function of the weight of the ball. Too much or too little and you can get some really high pressures. Go to the cannon pages where they shoot the cannons and talk to those guys.

I saw one cannon that had the breech plug threaded in like a black powder rifle, It should be threaded in at least as far as the diameter of the bore, then it could be welded by a certified pressure vessel welder who would heat it to 600 degrees and then weld it, then pack it in ashes and let it cool very slowly to preserve the integrity of the weld.


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