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.
Al Gore & Bill Clinton's final picture after Bill told Al, "Let Tipper hold yer beer, you come over 'ere 'n take a look at this!"
5.56mm
10" schedule 160 pipe has a pressure rating of 2950 PSI.
Perhaps some freepers with ballistics experience can tell us how much pressure we could expect when firing a 14 lb. ball with the three ounces of Fg (coarse) Pyrodex specified in the article.
Remaining embers has cost many an artillery man his life. This was a key part of the reload for black powder cannon...using a wet rag on stick to swipe the bore.
He might have done it just right, and have a high margin of safety. He might have overlooked something important, too... that thing would be a killer if it ever blew apart.
Off hand I don't know the yield on said pipe, but it should be sufficient for firing a bowling ball. At a weight of about 55 pounds per linear foot it would be pretty tough to tote around though.
I do agree that sewer pipe is a poor choice.
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