Posted on 09/27/2003 8:39:41 PM PDT by mhking
Ah, serendipity. Being in the right place at the right time.
As it happened, this fine and sunny September Sunday morning found me and a few others at the local gun range, sighting in- or trying to- some rifles. Some were cooperating, some weren't. A normal outing to the range, really...
Until this fellow pulls up and starts unloading a big 'ol hunk o' pipe.
I thought he was going to bury it as a new target stand or something.... 'til I saw the Bowling Balls. I then immediately knew it must be what some call a "punt" mortar! I'd seen similar handmade ones on the 'net and in magazines... naturally, we all completely forgot about our own rifles for the moment.
The Gun Range is a nice place- raised, covered shooting line, plenty of tables, well-kept grounds. The first line of targets is at 100 yards, with small berms and pipe target stands at 200, 300 and 400 yards as well, plus a trail/road to drive up to 'em if you need to. And at 500 yards, right at the base of the stand of trees off in the distance, is a full-size steel cutout of a moose, painted day-glo orange. Above, the guy with the mortar is pouring in some three ounces of Fg (coarse) Pyrodex black powder...
This thing is huge! Probably weighing some 150 pounds, half-inch-nominal wall pipe with a massive two-inch-thick breechblock welded on one end. The touchhole or fuse passage leads to a small "chamber" in the center that holds the powder in a single spot, rather than letting it cover the whole 8.5" bore.
Crude, yes, but it works. The owner is reluctant to do any additional welding on the pipe, for fear of making a weak or brittle spot, so he just stacks up whatever's handy to hold it, oh, 'bout there or so. This thing's so cool I want to make the guy some adjustable legs like the old 4.2" Chemical Mortar had....
Three ounces of Pyrodex, an old garage-sale-special bowling ball, an old chair and some sewer pipe... Fire in the hole!
He's not running, but he ain't dawdling either! Let's see, the fuse burns at about one minute per foot, there's about six inches there... dum da dum... carry the three...
HOLY FREAKING BATTLESHIP MISSOURI! By the time the shutter snapped, the ball was, in relation to this picture on your screen, about six monitors up and climbing. It was whistling. I lost track of it since I was trying to get the picture, but the guys say it cleared the treeline by probably another hundred yards.
Let's do that AGAIN! Rod out the fuse hole, make sure there aren't any errant embers, pull the mortar up out of the divot it created, weigh out another charge of powder, another bowling ball... This time I was watching downrange with the camera pointing at the cannon... Holy Creeping God, ladies and gentlemen! That ball was screaming out of there! I'd wager it landed over 600 yards downrange.
I should have brought out my Radar Chrony. I'd guess that ball wasn't moving over 700 fps, possibly as low as 400 fps, but jeez, think of the mass! That ball's what, eight to ten pounds?!? What's the Hatcher's Index of a projectile weighing fifty-thousand grains moving at 400 fps? "Body armor" against this thing is eight feet of dirt over a concrete bunker!
Think Grandpas' old thirty-thirty is a kicker? How about a hundred-plus-pound gun that pushes itself into the dirt six to eight inches each time it goes off? This is not a shoulder arm.
After all four balls were expended, we helped load it back in the guy's car. I noted that there were some divots from earlier shoots... he said he gathers up old balls whenever he can find 'em, then when he has a few, on a nice day he'll come out and blow 'wm downrange. Says it always draws a crowd. I said "so there's already a few balls out there in the swamp, eh?"
"Oh, more than a few, yeah."
He says he also has a short cannon that takes small tomato-sauce cans and another mortar that takes soda cans. The soda cans, it seems, don't hold together well- the force of firing blows the can off the concrete fill, which then blows up in the air.
Besides, he says, NOTHING beats seeing that bowling ball howl downrange as far as the eye can see.
I agree. :) The pictures don't do this justice; this is something every Tinker or gadget freak should see in person at least once in their life.
Our gun mounts were the same, a few 2x4s and a shovel to set the back end of the cannon into the dirt. We only used a couple of tablespoons of black powder, a half sheet of newspaper for wadding, and a baseball bat for the ramrod.
Our range was about 400 yards, and we were accurate enough to put the beer can between two tree trunks about 10 feet apart. Thanks for the memories...
A bit of a tight fit. If you use schedule 60 seamless X-60 pipe you would have a better fit and lower pressures.
My .223 cents worth.
Looks like fun.
It appears that he welded a piece of plate to the pipe. He should have used a cap instead.
This is the same reason that you never see a rectangular pressure vessel.
Of course I have been wrong before!!! Just ask my wife!
;<)
As Red Green says, "Carpe ductum"
All you need is the welding, powder and shot.
Great idea. Eaker does have a history of things like this blowing up in his face!!!
Old ping list mistake!! Won't happen again!
I think we need Squantos too. Safety, ya know!
I'm not a pipe guy, but would gas pipe, as in mains, be a better choice?
This looks like a fun project though I have a couple of improvements in mind.
First, an electronic ignition sytem, such as a model rocket ignitor system, would be far safer than a manual fuse.
Second, some sort of carriage type base, where the barrel sits on a slide and has springs similar to heavy duty trucks to absorb recoil. And, mount it all on a trailer with swing out down jack plates at the corners for stability.
The modeling portion of R and D starts tomorrow.
I can fine tune the calcs. Monday at work.
We could make this happen!!!
Eaker this might work. I know the police chief at Jamaica Beach on Bolivar. He was in Rotary with me when he was a Lt in Missouri City and I would be happy to ask him.
Pipe engineering and design is part of what my firm does. We build grass roots natural gas compressor stations.
Post 79 details preliminary specifications.
We also need someone to deterime if a 9.5" bore is suitable for a 8.6" bowling ball. Schedule 140 pipe would give a bore of 8.75".
Anybody here know which would be better???
And here's Al Gore teaching the folks on the range about mortar safety.
Well hell, there goes the fun!!! ;-)
Shoot Move Communicate .... and watch the fireworks.
I wouldn't use a trailer - there's a lot more play in a trailer than you would think. But I think a permanent carriage system (probably some sort of cradle) would be a good idea. I wouldn't try to absorb all that energy - let Mother Earth do it - she's used to it.
It seems you have most of the material needs worked out. I will look for a location if that's ok with you.
I would really be interested in how far the shot will travel and thought perhaps bobbyd could stand down range as a forward observer? He might even use his baseball skills and catch the thing!
Famous last words: "Hey - I thought YOU were "Sponge" - and do I see something bright down in there?"
No gunner worth his salt would have any vital portion of his anatomy covering the muzzle.
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