Author Topic: My latest gun a 47m/m cannon (Read 1751 times)

Will Bison · « **on:** March 02, 2003, 12:27:49 PM »

Lets see if this works.

http://home.earthlink.net/~willbison

This is the gun I built about 10 years ago from a Jap 47 m/m anti-tank gun tube. The gun comes in at 350 lbs and fires a 20 ounce ball on top of 4 ounces cannon grade.

It is made of red oak and has three limber boxes built into the carriage. The whole gun sits about 38 inches high and is 7 feet long and 40 inches wide.

One person can handle it but two is better.

Jeff B. · « **Reply #1 on:** March 02, 2003, 12:34:57 PM »

Will,

That's quite a nice piece you have there! Looks like it's a blast to shoot. It looks as though you put a great deal of effort into your project - it shows! If you have any other pics of it please fire them our way.

Cat Whisperer · « **Reply #2 on:** March 02, 2003, 01:07:34 PM »

Will -
What range do you get? Ammo? Moulds? Targets?

Sounds like a marvelous center of attention for quite a few occasions.

Cool shootin' iron.

Will Bison · « **Reply #3 on:** March 02, 2003, 01:45:16 PM »

I just found this site and this was my first time putting up a web page. As soon as I get on the front edge of the learning curve I'll post some additional pics.

I will give you some additional info however. This gun is number 27 for me, either built from scratch or a restored piece. I don't count toy guns, only those over one inch.

My largest was a 155 m/m howitzer. Wayyyyyy too big.

The bore is rifled at one turn in eight feet and we use a patched round ball in it. The ball must be driven in with a hammer. I am seriously considering having the thing bored smooth. Just happened I found an old tube that had been cut for scrap so I used it.

Originally the thing had an eight foot tube and fired a 6 pound shell at 2800 fps. This of course was all with smokeless powder. It was logical to take a 35 inch section of scrap and build a gun.

My machinist built a wonderful ball mould that comes out at 46 m/m. This allows the ball and patch to go down the bore with a minimum of hammering. Doing this all over, my advise is smooth bore. I like to shoot canister and grape and rifling blows the pattern. Most smooth bore guns will out shoot me.

I tried to run the ball on my chrono but the muzzle blast makes a mess out of the screens. Average velocity over 880 yards was 680 fps. That was using high speed digital video where the muzzle blast and the point of impact could both be picked up. Knowing how many frames per second the camera runs at and some simple math discloses the story.

I,m into this whole thing for 1500 bucks not including labor. Working a few hours a day we (two of us) had it out of the shop in 4 months.

It is not a replica of anything but rather a fun shooter. We went with a splt trail for simplicity and wanted it to look a little older than a Civil War gun.

Recoil is violent and the muzzle blast is impressive. When shooting blanks for special events, we regularly set off car alarms.

Cat Whisperer · « **Reply #4 on:** March 02, 2003, 02:01:05 PM »

Ahah! Mould - what is the shrinkage for a given alloy? (i.e: could you measure both the mould and the ball produced and give us some dimensions for the alloy you use?)

#27 ? that sounds like an addiction. Drive on!!

155's are cool at many thousands of meters. Too heavy for me. Otherwise I'd consider 8" mortars.

How does patching with a thinner material work? I'd be a little nervous hammering a round down onto a pound or so of powder.

We'd love to see some pictures of the moulds too.

Thanks,

Will Bison · « **Reply #5 on:** March 02, 2003, 02:25:28 PM »

Cat;

I can get way over four miles with this gun. Not that there is any reason to do so. I have access to a lot of dry lake beds and they offer a good flat surface along with kicking up a good puff of dust from impact of shot.

We just measured the impact with a GPS last summer. Keep in mind we use a 5-1 shot to powder ratio. For standard target shooting we reduce to two ounces of cannon and typical targets are 55 gal drums full of water at 200 yds. A dead center hit is impressive.

For cannister or grape, 100 yds and cardboard boxes or 4x8 sheets of drywall work well. The drywall works very well as hits are easy to see and creative kids can draw pictures on it.

For grape we use 24 ounces of .50 balls and three ounces of powder. That comes out to about 60 balls +-.

Cat Whisperer · « **Reply #6 on:** March 02, 2003, 02:36:11 PM »

Will -

FOUR MILES!! Thats one or TWO mountain ranges over (here in Virginia). That's why I've generally stuck with mortars. I lile to see what I'm going to hit. (Although I have cleared the mountain at the back of the range.

The drywall sounds like a keen idea too. 55's are a bit too big, but I do remember what a high school friend said about putting M-80's in a stock watering tank.

Will Bison · « **Reply #7 on:** March 02, 2003, 03:18:41 PM »

The mould, what a simple operation. A piece of round bar stock (mild steel) is utilized. A fly cutter makes a half round cut in each piece then the two halfs are put back together and holes drilled for the alignment pins.

No handles are used just a simple furniture clamp. The lead takes about 4-5 minutes to harden. I use pure lead from the scrap yard and I recover as many balls as possible. I add just a tiny amont of tin, less than 1 percent. This makes the lead fill out better. The bigger the bullet the easier it is to cast. We use a coleman stove and can melt about 40 pounds at a time.

None of this is rocket science, it is simply taking on each thing as a project and working out a solution.

Shrinkage rate for lead is a variable dependent on temperature and other inclusions. One percent or less is normal and less is more normal. This is then corrected with patch thickness. Working out the math was not too difficult. There is a lot of slop factor.