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.
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.
All true. It's apparently the finger holes in the ball that add to the effect. Though the zipperlike-noise of a large- bore projectile fired at a direct flat trajectory has a certain charm of its own. From the firing end.
-archy-/-
I'm thinking this guy's a few reloads short of a 'hold muh beer' alert.
Read the part about how 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; he's using the same high-low pressure chamber technique that lets aluminum-barrelled weapons like the M79 and tear gas grenade launchers function with aluminum or plastic barrels. In their case the pressure is contained in a high-strrength section of the cartridge case head; in the case of these guns, in a pressure chamber in the base of the barrel.
With the 40mm M79/M203 round, that works out to around 3000 PSI contained within the aluminum high-pressure containment chamber in the base of the shell, which ruptures a blowout disc and is then vented against the bottom of the 40mm full-bore diameter projectile. Once the projectile overcomes its inertia and begins moving, the pressure is not only reduced due to the correspondingly lareger area of the projectile's base, but as it moves further up the bore, the initial pressure drops off to even less. Same idea with the bowling ball launchers. Or with some of them, anyway.
-archy-/-
There are always shortsighted individuals with no appreciation for the application of genius on a large scale.
Nice stable platform, hmmmmm. With lots of room for a long gun tube, hmmmmm....
Or synchronicity, if you follow the philosophia of Carl Gustav Jung.
-archy-/-
2145 7.62X54R RUSSIAN 180gr. SP Sellier & Bellott
I've not gotten a mile out of mine yet. Next time I'm out your way for a visit or conference, I'll toss one in the back of the truck and warn you I'm headed your way. Till then, *Go here* and drool.
-archy-/-
You don't have to remove the magnesium wool, and the pure oxygen atmosphere content inside the bulbs promotes a hotter ignition anyway. A very light coat of white carpenter's glue or rubber cement and a dunk in Bulleseye pistol reloading powder results in a fine electrical ignitor that's proved nearly 100% reliable for me, so long as I'm neat about attaching the electrical leads to the small wires of the flashbul
You'll find some bulbs have a bluish coat or tinted coationg on them. I've tried the both with the coating left on and with it scraped off; same results. In fact, as the stuff melts to a sticky goo from the heat of the bulb's ignition [and prevents shattering of the glass bulb's case] it seems to be hot enough to ignite a powder coating itself. It works fine, without compromising the integrity of the bulb itself.
-archy-/-
Thin barrels burst sooner than thick barrels.
From magnesium sheep??? (Sorry, I couldn't resist.)
I don't like bullet launchers that misbehave. I was trying to develop a cheap target load for my Colt Government Model in 38 Super (I should have kept it as a collector's item). I had a nice, mild target load in .39 Special using flush-seated wadcutters, and a light charge of Unique. I figured it would work okay in the Colt, but might not cycle the action.
I made a few unloaded dummy rounds, and found to my amazement that they fed perfectly, even when I cycled the slide slowly. So I loaded a batch with Unique using the same load as in a .38. What I forgot to consider was the .38 Super case was much shorter. What was a sensible load in the revolver was a compressed powder load in the Colt.
The first round worked, but I was puzzled by the loud report, and heavy recoil. The second round was KA-BOOM, and I saw black smoke blasting out from all the seams of the handgun.
By now, a little light went on in my head. I found the empty brass, and a chunk of brass was blown out of the case. It blew out where the case head was unsupported.
Compressing the powder changed its burning characteristics into something more like a detonation. The first case held, the second one didn't. The hot brass and gas hit the rounds in the magazine below it, and left scorch marks inside the gun, including the insides of the grips, where the blast came out the witness holes in the magazine.
I was grateful for John M. Browning's design, since the major damage was only embarrassment. I pulled the other rounds, and out of each one came a tiny compressed pellet of what used to be Unique. Some handloaders screw up by using the wrong powder. Me, I learned my lesson about highly-compressed smokeless powder.
The biggest fireworks I ever saw in artillery was when guys got lazy about burning the unused poweder increments, and just threw them, from a distance, onto a bonfire. They'd just burn with a faint "whooomp", but one hell of a column of flame. I got one picture of a hundred-foot-tall flame from one bag.
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