I'm thinking of a trap or tank that I can test pistol loads. Imagine the kind you see on cop shows that they can test fire weapons. Look at:
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I'd like to incorporate a chronograph and be able to test pistol function in multiple shots. The unit will have to be quiet enough to keep the neighbors oblivious and the fumes will have to be vented. Has anyone seen plans for such? The cheapest commercial ones are thousands of $, and no chrony. It would seem the perfect way to work loads in a very short time.
I was thinking of an automated computer controlled conveyer system to transport the empty shells through a cleaning cycle and back to the reloading press. The powder charge could be adjusted by computer to the desired FPS and the fresh reloads could be conveyed back to the test chamber. (just kidding)
The one glaring problem with your requirements is the crony screen spacing. It runs between 4 and 10 feet between the start and stop screens. So you would need between 4 and 10 feet of free space before you could impact your catching media and even then, splashing and so forth of the water may have negative issues with your electronic screens
Gunner
"Lenin called them "useful idiots," those people living in liberal democracies who by giving moral and material support to a totalitarian ideology in effect were braiding the rope that would hang them. Why people who enjoyed freedom and prosperity worked passionately to destroy both is a fascinating question, one still with us today. Now the useful idiots can be found in the chorus of appeasement, reflexive anti-Americanism, and sentimental idealism trying to inhibit the necessary responses to another freedom-hating ideology, radical Islam"
Bruce C. Thornton, a professor of Classics at American University of Cal State Fresno
Yabut the unit doesn't have to be very wide. I have a blank 25' wall on the right side of the garage. You ARE going to help me automate the Dillon press when I get to it! Gotta' be easier than stuffing wire in holes. I'm in no hurry, I'm just finishing up the main bench in the shop/garage. The Dillon will eventually be mounted on a steel pedestal bolted to the floor. The trade-off for the entire garage is I have to make a shitload of book shelves and such.
"Lenin called them "useful idiots," those people living in liberal democracies who by giving moral and material support to a totalitarian ideology in effect were braiding the rope that would hang them. Why people who enjoyed freedom and prosperity worked passionately to destroy both is a fascinating question, one still with us today. Now the useful idiots can be found in the chorus of appeasement, reflexive anti-Americanism, and sentimental idealism trying to inhibit the necessary responses to another freedom-hating ideology, radical Islam"
Bruce C. Thornton, a professor of Classics at American University of Cal State Fresno
Put a few spaced sheets of thin mylar or polyethylene film between electronic screens and the bullet trap. The bullets will punch small holes in the film, but the film will still intercept the splash. Every so often, replace the film.
Son..I work in the Manufacturing bidness....unique ideas are where the money is at. I never laugh.
I do however chuckle in wonder at how some things are done that Id not seen done before.
Gunner
"Lenin called them "useful idiots," those people living in liberal democracies who by giving moral and material support to a totalitarian ideology in effect were braiding the rope that would hang them. Why people who enjoyed freedom and prosperity worked passionately to destroy both is a fascinating question, one still with us today. Now the useful idiots can be found in the chorus of appeasement, reflexive anti-Americanism, and sentimental idealism trying to inhibit the necessary responses to another freedom-hating ideology, radical Islam"
Bruce C. Thornton, a professor of Classics at American University of Cal State Fresno
A ventilated tunnel is usually what's used in industry. You can build "silencers" to fire through as long as they aren't attached to the gun. I've seen one guy who used a stack of tractor tires on edge to shoot through as a baffle box, apparently helped enough to keep the neighbors from complaining about his outdoor range. For inside use, the usual trap makers have function-firing devices for gunsmithing that trap both muzzle blast and projectiles, no room in there for a chronograph. The one I saw at an auction from a gunsmith's business was like two armor-plate 55 gal. drums stacked up on their sides, one did the projectile containment, the other did exhaust filtering and had an additional filter canister on the outlet. The outlet would have gone through the wall like a dryer vent. There was a slit rubber screen to push the muzzle through when firing. They're not cheap to buy and have fairly stringent ratings for what you can fire off in them. I supposed you could make/buy steel tubing thick enough to make a tunnel type of gizmo, it'd have to be big enough in diameter that the muzzle blast wouldn't cause false triggering on the chronograph screens. You'd then use a regular bullet trap at the end. Might just be easier to excavate and make a concrete tunnel thick enough to stop richocets.
Chronographs are so cheap now that you'd be crazy to design one from scratch. I've gotten Chronys from gun shows for as little as $25. A recent Nuts and Volts issue had plans, though. Far more desirable would be a pressure curve monitor, these are available, with ballistics software, but fairly spendy, about the cost of a decent rifle.
The spacing between my chrony's screens is 12 inches. It does want a few feet of standoff distance so smoke, muzzle flash and gasses don't screw it up. A partition with a small hole thru which the bullet could pass might significantly reduce the standoff distance.
Standard Chrono at USPSA matches is the CEDHK Millenium (now millenium II). Get the infrared lightingoption if you are going to use it in a tunnel. Screen spacing is 24" (I think). Should be about $250, and it's the last chrono you will buy. The little shooting chroney F1's are fine, but I've seen them vary 50 FPS from unit to unit.
Sound baffles---Old tires on edge, barrel in a barrel with fiberglass in the void, lots of ways to get there. A word of caution---those gases you are trapping can be flammable. Build it too "tight" and it will be quiet, until a few shots into the string when the gases ignite and the backblast flame trims your eyebrows. Kind of fun to watch--but I get amused by the darndest things.
$79. I have not seen a 10' width crono ever. You need a steel plate to deflect the bullets down to a trap, You could have a large pile of sand in front to catch the bullets, but you want a thick steel plate to stop any getting through. Traders Sports in Hayward, CA years ago, had an employee killed by a bullet coming through the wall behind the range. The years of shooting had thinned the wall. To quiet the shooting you could have sound absorbing material in a long tube or square chamber to shoot through.
so, I don't know anything about your application, but it seems you are working very hard to do something very simple. can't you fire your bullet down a small tube (say 4 or 5 inch diameter) pretty accurately? if yes, can't you align a light beam so the bullet interrupts it? if you knew the length of the bullet, a single beam would do the trick - just measure how long the interruption is - if you don't know the length, then two beams separated by a known distance will do the trick. After the bullet passes the beam(s) you can do anything you want with it, you've got your measurement. Now, if you want to measure the spin, that takes a bit more, but to just capture speed, a couple of laser diodes, a couple of photodiodes and a storage scope will do the trick - don't want a storage scope, then an oscillator and a timer / counter and a flip flop will do the trick - reset the timer when bullet passes first beam, halt it when it passes the second beam - set count rate for something convenient (for example, 1 Mhz to get time in microseconds)
Steel plates are going to be noisy and ricochets may happen. Only time I got shot in the service was at the firing range and a pistol ricochet got me. Plus the you have lots of lead particles airborne.
"Lenin called them "useful idiots," those people living in liberal democracies who by giving moral and material support to a totalitarian ideology in effect were braiding the rope that would hang them. Why people who enjoyed freedom and prosperity worked passionately to destroy both is a fascinating question, one still with us today. Now the useful idiots can be found in the chorus of appeasement, reflexive anti-Americanism, and sentimental idealism trying to inhibit the necessary responses to another freedom-hating ideology, radical Islam"
Bruce C. Thornton, a professor of Classics at American University of Cal State Fresno
I thought I offered two solutions - one that would employ off the shelf test equipment, on the chance that the OP had such things, and one that would use about $5 in parts and take an hour to build - a storage scope is no longer particularly rare, and they can be had cheaply - and even without storage, setting up a regular old scope to trigger properly and then looking at it before the trace fades will do the trick - but if that is all too complicated, you could try this - put a piece of film in your (dark) long pipe. trigger a strobe when the bullet passes - the length of the shadow on the film will show how far it traveled during the flash, and all you need to know is tue duration of the flash - old left over camera strobe, $1, cheap film $5, - is that simple enough?
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