So, I’m getting into reloading ammunition. Which means I need to store gunpowder. And it would be convenient to be able to store assembled ammunition in the same place. Legally, assembled ammunition must be stored in ``a securely locked container or receptacle that cannot easily be broken into.’’ For safety, gunpowder should be stored in something that is vented and/or will fall apart (thus becoming vented) should pressures inside it rise. My plan is for basically a plywood cabinet that I can bolt a press to the top of, and has a door that I can lock.
So after all that, the question, to which I hope there is a factual answer, is: how could I assemble a cabinet out of 3/4" plywood such that the seams will fail gracefully well before the pressure inside turns the whole thing into sharp highspeed matchsticks?
I guess that’s an option. Then, though, I’d need to figure out how many holes it takes to vent the thing adequately. And I have no idea how to go about that. So I figured if I built the thing so it would fall apart should there not be enough holes, I could just drill a few as a first line of venting, but know that if that’s not enough, it will still be safe…
Viking, if you’re talking about modern smokeless propellant there is little use in making a breakaway cabinet. Smokeless has only a moderate burn rate unless it is constrained, say a chamber in a gun. As pressure goes up the burn rate rises dramatically. A can of smokeless that catches fire will split the container and go “fwoosh” more than “boom.” Smokeless isn’t even classified as an explosive for this reason. Do keep your primers stored separately though.
Black powder is another matter. It is classified as an explosive and does not need to be constrained to explode. In both cases protect your powder from fire as much as possible. I’d suggest making a box from two layers of sheet rock which actually does break apart easily but is also an excellent fire barrier.
Padeye, yes I am talking about modern smokeless. I guess I’m just not sure how constrained is constrained. Powder is ridiculously over-priced locally, and haz-mat shipping adds a bunch to the cost of getting it mail order, so buying 5-10lbs at a time makes a lot of sense. Is that quantity in a handful of cubic feet constrained? My order-of-magnitude guesstimates suggest that if there is no gas leakage, and 10lbs powder turned into 10lbs of gas with an average molecular weight of 20 or so in a 12ft^3 box, we’d be talking 60 atmospheres or so. Of course, first year chem was long ago, and my assumptions may be wrong. But my conclusion was that either the venting needed to happen as fast as the powder burned, or the cabinet had to be weak…
I don’t think that is nearly constrained enough to accelerate combustion like in a firearm chamber.
I think you’re working at cross purposes here. You need a reloading bench to be strong and rigid but you want to make it fall apart easily at the same time. If you don’t have space for separate containers how about this; make your bench/cabine strong and rigid but make one back panel where the powder is stored out of sheet rock? Worst case scenario the house fire gets to the powder it just blows out the back panel of that section. If there actually is a fire it will burn away the outer kraft and weaken the sheet rock by the time the powder ignites anyway.
Drop me a line off the board if you want to discuss further. I’ve done some other things with my powder storage that may work for you. padeye@padeye.net
Thanks, that sounds like a good idea. I’ll just put a square foot or so of sheet rock (or maybe even sturdy metal gridding) behind one shelf. That should be perfect.