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We need a tube.

A bowling ball is 8.605 inch in diameter.

Is there a seamless steel pipe or tube with an Id of 8.625. Maybe a gas line or oil line pipe? How thick do we need the side walls.

My idea is to make a breech plug much like the breech plug in a muzzle loading rifle. In this plug will be the powder chamber. The Plug would screw into the end of the tube and butt up against shoulder in the tube. The plug would then be pinned to keep it from unscrewing. The trunnions would attached to the breech plug

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I've seen bowling ball type mortars made using a large compressed gas cylinder cut out at the base, with a ball joint welded to the top (where the manifold used to be) and inserted into a base plate. The tube is then supported by legs (surplus mortar legs or other).

Looked good, shot good and inexpensive.
 

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Now you've done it! Bowling balls. They are commonly available at every third or 4th yard sale for $1 or so. I have the micrometers to go up to 12" but it'll be this spring before yardsale season opens again.

What I want to know: is there a stanadard size for the bowling balls?

If there is then there is the possiblity of finding a standard size tubing. I think it was on the cover of Small Arms Review (I could easily be mistaken) that I saw within the last year or so where someone took a high pressure cylinder (oxigen or argon or ...) chopped the bottom off and made a blackpowder mortar from it using bowling balls.

If this is the case, again, what are the standard size bowling balls, and is there a standard ID for these cylinders?

Firing something that big has got to be breathtaking.
 

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I'll bet the price would be right. I know from fire extinguishers and scuba tanks, if the tank doesn't pass the test, the testing agency MUST put a sizeable hole into the tank. Of what value is it then? Depends on where the hole is, but for this use it should be OK (given a reasonable use of "common" sense).
 

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Heck, I'm checking with my local scrapyard, they cut their tanks in half. I'll let ya know...ya figure 8 5/8 inside diameter?? :D
 

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I talked today with one of the local welding gas distributors about tanks. He said that they did all their hydrostatic testing in-house & that that they'd just gotten a bunch of tanks from another company that weren't any good that they'd taken to the scrap yard. He said they cut off the valve end when they got rid of them. He mentioned, also, that several people had gotten them to use as 'cow bells'. So next time I see him he'll probably have an old one for me.
 

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JeffG -

Since this would make a good topic by itself, I'm starting a new thread - so look under the topic relating to clearance between bullet and bore.
 

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How long is one of those tanks? Some where I saw where the recommended mortar bbl length is twice bore diameter. Allowing say 2 inches for the base plug 20 inches sounds about right. Are those tanks 40 inch of usable length?

A O2 tank is one of those thing that's always around but you never pay attention to...they are green aren't they!!!
 

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C'mon you guys we are thinking too small, I want one of these! :eek:
 

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JeffG - Who says we DON'T want one (or more) of those as well.

Having a 4.5" that weighs (tube and trunion) 103 lbs. My interest in owning anything bigger has decreased (I know someday I'll have to have the hernia on the other side fixed too).

So everything that I build now is required to be easily transportable by ONE person.
 

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Ya, it sounds close to the way been thinking...hernias bein' what they are :wink: I don't want to get another one. If I could figure out how to winch the bad boy onto the trailer, I'd be making it bigger, too. This bowling ball thing with the sched. 100 pipe or gas cylinder, might be the ticket. :D
 

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I'm not sure, I have a call into a guy who can tell me, and if not, he will recomend something...I 'll report back. :D
 

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Sch40 & Sch80 pipe are both welded seam pipe so Sch100 is probable welded seam pipe 8)
 

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Gentlemen, I have 2 bowling ball mortars. Both made out of oxygen tanks. The tanks must measure 29 1/2 inches around the outside. I cut one 3' and the other 4'. The extra length does produce more velocity, more distance. I fire 1/4 pound 1/2 pound and have even done a full pound. (ball flew about 3/4 mile on the full pound) welded 2'' trailer ball on the bottom, used a truck roter and a patio umbrella base as baseplates, one inch and 2 &1/2 inch pipe for legs.

E-mail me [email protected] for a photo of 6 different bowling ball mortars

Jan
 
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