Bowling ball specs

[Dictator]

I think I've seen this info on here before, but what is the powder chamber dimensions & recommended bore length for a bowling ball mortar? I getting an urge to build one

[Double D]

Yep, we got that for you! Check References  Scroll down aways and you find the info you are looking for as far as ball and bore dimensions go.

There is no "spec" for the powder chamber. The typical welding tank bowling ball mortar has a fairly small powder chamber.  If you use the recommended formula for minimum breech dimensions you could have a powder chamber that is  1/3 the diameter of the total diameter of the barrel at the breech. (Barrel wall thickness at the breech shall be no less than one caliber.)  

In theory if you had a barrel 10 inches in outside diameter. You could have a powder chamber  3 1/3 inches in diameter.  That is a big powder chamber.  

I haven't got my hands on a welding tank yet to measure the powder chamber.  In fact that is one of the mysteries we have explored on this board.  Which welding gas tank is the right tank?  The O2 tank is a hair to small!

[Dictator]

Thanks DD
 That does kinda follows with what I've seen at some shoots. I've seen anywhere from a 3"x3" size to 1.750"x2". I was thinking 2"x2". A 3" chamber does sound big. The 2 mortars below were shooting balls at a target 1000 yrd away. Some of the shots went way beyond that range. I didn't get a chance to ask them their loads as I was, shooting, myself down the line, but judging from the blasts, they were pretty healthy loads. How much powder fits into a 2x2 or 3x3 chamber? I've posted a print I found somewhere, & it has a bigger 3" chamber.
 Also, what is proper bore length? I'm thinking app. 2.5x bore diameter or roughly 20". What do you think? I don't want to make a howitzer.

[Double D]

I believe if you look at either N-SSA or the Artillery Association rules require the bore for the ball be two calibers.

[Cat Whisperer]

I believe if you look at either N-SSA or the Artillery Association rules require the bore for the ball be two calibers.

Two calibers is what we've always talked about being the standard length for a mortar tube.

Longer if you want more range for the same powder.

Shorter if you want more smoke and greater muzzle blast.

A one-caliber long golf-ball mortar with max charge (or 1-1/2" firecracker) will max out at 8' range going about 8' high as well.
That's at 45degree elevation and FFFg powder.

[GGaskill]

An 8 inch M1861 mortar has 10" of straight bore and 6" of semi-ellipsoidal chamber.

[12741]

I have recently built an o2 tank bb mortar following using "Florida BB mortar" plans. My powder chamber is 2in. dia. by 2.5 in deep.It will hold 5 oz but so far I have only fired 2 and 3 oz charges at high el. and short range. The tank to use has "DOT 2265" stamped on the shoulder.It is slightly shorter and fatter than the more common ones which are stamped 2400. Hope this helps.

[Dictator]

It does help. Thanks much---Joe

[Dictator]

Hey 12741,
 Where did you get plans for your "Florida BB Mortar"?

Thanks much,
Joe

[w a tyrrell]

Joe,

On page 13 of this thread on a post dated 2/27/04 are the specs for the "Florida Bowling Ball Mortar".  The length of the trunnion should be 13.5" if you use full 2" stock for the carriage.  I'd be happy to discuss the details with you.  772 589-0488.

Best Wishes,  Bill

[Double D]

Here is a Link to Bill's post. A Florida Bowling Ball Mortar

Hey Bill, nice to see you again, don't be such a stranger.

[Dictator]

Thanks much guys. Looks like I have a nice winter project