Author Topic: Bowling ball mortar  (Read 4812 times)

0 Members and 1 Guest are viewing this topic.

Offline SLEEPY BEEPER

  • Trade Count: (0)
  • Member
  • *
  • Posts: 83
Bowling ball mortar
« on: July 07, 2004, 07:23:41 AM »
Hi, Just wanted to thank the people that posted information on bowling ball mortars made from O2 tanks. My new mortar was proof tested on the 4th of July. With 12 oz. GOEX 3F, 26 pounds of bowling balls (2) and a long fuzz. The barrel held up great. The sledge, well that needs to be rebuilt (broke in half). The mortar was built along the Florida mortar plans. I added 4 heat-shrunk band for looks. The bands give it an old look (not an O2 tank look). Thanks again.

Offline Double D

  • Trade Count: (3)
  • Senior Member
  • *****
  • Posts: 12609
  • SAMCC cannon by Brooks-USA
    • South African Miniature Cannon Club
Bowling ball mortar
« Reply #1 on: July 07, 2004, 10:31:26 AM »
No wonder your sled broke you were grossly over loaded! 5250 grs.!!! you are lucky the mortar held together and no one was injured.  You need to closely inspect the mortar for broken welds and cracks

What is the diameter of you powder chamber! From that I will give you you proper max load.

Post some pictures.

Offline SLEEPY BEEPER

  • Trade Count: (0)
  • Member
  • *
  • Posts: 83
Bowling ball mortar
« Reply #2 on: July 07, 2004, 11:25:29 AM »
It was a proof test. There was nobody within eye sight of it (I was behind a dirt bank). If it was going to come apart. That's when I wanted it to. Now I can relax when I stand next to it, and shoot 150 yards. I've already inspected the welds. They are fine. Maybe some people think over loading a gun once as a proof test is silly. But it makes me feel better. I have read proof loads should be double normal loads. But what is normal for something like this? And what kind of steel are O2 tanks made out of? It was an extreme test. But it was done safely. If I build another. I would do it again. Only take off the sledge, and prop it up with sandbags.

Offline w a tyrrell

  • Trade Count: (0)
  • Member
  • *
  • Posts: 11
Bowling ball mortar
« Reply #3 on: July 07, 2004, 12:08:58 PM »
Glad to hear about your proof test.  I didn't proof mine (Florida Bowling Ball Mortar).  Probably should have.  Have you done any further shooting/tests?  I'd love to see a picture.

Best Wishes,  Bill Tyrrell

Offline Double D

  • Trade Count: (3)
  • Senior Member
  • *****
  • Posts: 12609
  • SAMCC cannon by Brooks-USA
    • South African Miniature Cannon Club
Bowling ball mortar
« Reply #4 on: July 07, 2004, 12:30:07 PM »
The whole theory of proof loading is subject of great debate.  The typical position in the U.S. is to proof the design, but the proofed piece is never used again, and is saved for reference. Very specific measurements are taken before and after the proofing.  Proof loads are carefully calculated to predetermine pressures and produce specific values.    Proofing stresses the pieces and creates weakness. Once the design is proofed that is usually sufficient. Further proofing of each piece of the design is not considered necessary

When I went to gunsmithing school, in our business law class as well as some of the gunsmithing classes they told us there are no U.S. standards for proofing.  If you proof  a firearm and then transfer it to someone else you are liable for  it if it fails.  There are proofing procedures as part of destructive testing. But those pieces are never used except for further testing.

Proofing as done in Europe is done to every piece under strict  controls. Here's a link to  The Birmingham Gun Barrel Proof House  the talk about how proofing is done in England and Europe.

Sounds like you took prudent action for firing you first shot,  I would continue taking those steps for a few shots until it's clear you have not  broken anything from the overload.

But post some pictures, we all want to see your gun!

Offline SLEEPY BEEPER

  • Trade Count: (0)
  • Member
  • *
  • Posts: 83
Bowling ball mortar
« Reply #5 on: July 08, 2004, 01:59:46 AM »
I will try and post a picture. I tried once and failed. But will try again with some help from a friend. I'm not a big computer person. And the abbreviations in the directions for posting pictures throws me. Next week I will start firing the mortar to develope a range curve. We have a local cannon shoot at the end of the month. I need to get out and practice with this new gun, so I don't make a fool of myself at the shoot. The biggest problem I see is getting 10 bowling balls that weigh the same for the shoot. So far I've collected 12 bowling balls. But they are all different weights. Does anybody out there know how much a 2 pound difference in the weight of bowling balls, will effect range at 200 yards? Half of the balls I've collected so far, are between 14 and 16 pounds.

Offline SLEEPY BEEPER

  • Trade Count: (0)
  • Member
  • *
  • Posts: 83
Picture
« Reply #6 on: July 08, 2004, 09:13:37 AM »
[url]

Offline Cat Whisperer

  • Trade Count: (2)
  • Senior Member
  • *****
  • Posts: 7493
  • Gender: Male
  • Pulaski Coehorn Works
Bowling ball mortar
« Reply #7 on: July 08, 2004, 02:34:06 PM »
Quote from: SLEEPY BEEPER
Does anybody out there know how much a 2 pound difference in the weight of bowling balls, will effect range at 200 yards? Half of the balls I've collected so far, are between 14 and 16 pounds.


From my experience with 4.5" and soda-pop-bottle caliber mortars, the heavier the projo the longer the maximum distance for a given charge.

I think it provides more resistance to the initial burn, allowing pressure to rise higher while the round is still in the tube, therefore greater velocity.  It may only be that the mass is greater and therefore the ballistic coefficient is higher and therefore greater range.



Anyone use a chronograph with their mortar or cannon?
Tim K                 www.GBOCANNONS.COM
Cat Whisperer
Chief of Smoke, Pulaski Coehorn Works & Winery
U.S.Army Retired
N 37.05224  W 80.78133 (front door +/- 15 feet)

Offline Double D

  • Trade Count: (3)
  • Senior Member
  • *****
  • Posts: 12609
  • SAMCC cannon by Brooks-USA
    • South African Miniature Cannon Club
Bowling ball mortar
« Reply #8 on: July 08, 2004, 03:26:51 PM »
I notice that you fellow trying to use Photo bucket hoave been having problems with it so I registered for a free account to see what's up.


To post a picture from photo click onthe window below the picture called Img.  The window will turn blue.  With the mouse arrow over the blue line click the right button on your mouse and a small menu will pop up.  Slide down and click on copy on that menu.

Open the posting window on Graybeard. Click any where in the window, then right click again and select paste from the  menu and the img link will appear like this.



Sleeper Beeper if you go back to your post that doesn't show the picture and only a red x and click edit you will see that you are missing part of the link.  You can copy the link like explained above and repost in that post.

Offline SLEEPY BEEPER

  • Trade Count: (0)
  • Member
  • *
  • Posts: 83
O2 tank mortar
« Reply #9 on: July 09, 2004, 07:09:53 AM »

Offline SLEEPY BEEPER

  • Trade Count: (0)
  • Member
  • *
  • Posts: 83
O2 tank mortar
« Reply #10 on: July 09, 2004, 07:14:18 AM »
Thanks Double D for working through the picture post for me. If I can do it, so can others. Show us your cannons and mortars. Once you have done it, it's easy. I used Photobucket. It worked well. And it's free.

Offline Double D

  • Trade Count: (3)
  • Senior Member
  • *****
  • Posts: 12609
  • SAMCC cannon by Brooks-USA
    • South African Miniature Cannon Club
Bowling ball mortar
« Reply #11 on: July 09, 2004, 09:46:50 AM »
Glad you got the pictures posted, but i owe the group and apology.

At the bottom ot the Post reply screen are some boxes that need uncheck inorder to post pictures.

Disable HTML in this post

Disable BBCode in this post

When you post pictures be sure that the little boxes next to these two options are not checked.

Sleepy with what I see in the background of that mortar I think you need som William Green plans, Jim Waits, would you agree?

Offline SLEEPY BEEPER

  • Trade Count: (0)
  • Member
  • *
  • Posts: 83
O2 tank mortar
« Reply #12 on: July 13, 2004, 07:44:29 AM »
I had a chance to start building loads for the new bowling ball mortar. It sure is fun to shoot. It doesn't take much powder. 280 grains will push a bowling ball 100 yards. 350 grains - 200 yards. Putting a film can of flour over the powder seemed to make the shots repeat better. Loading the barrel with it propped up to 80 degrease. Then lowering it to 45 degrease to shoot, gave longer ranges then loading and shooting at 45 degrease. Probably because the flour and powder was mixing at 45 degrease? Also, I really sore today. Shooting out bowling balls, walking down to get them and bringing them back. Is more work then I am use to. You got to love it. And good exercise to. It's interesting the extra thrill I get shooting the bowling balls over my concrete filled can shooting mortars.