I just got a shipment of these unique things in and I'm impressed.
Very simple design. I really like the way the gas pneumatics work. No balls to reset like the Moscart type grenades.
Initially I was worried that an aggressive stomp would crack the plastic lid. Now that I've seen the thing, I note that the trigger plate/lid is heavy ABS. Once the trigger plate pushes down, four heavy standoffs (4 fins shown in Fig. 3) bottom out on the inside of the bottom half of the mine and support the top.
The brass insert in the centre of the trigger plate is about 5.5 turns deep. Lots of threads to engage on so I doubt it will strip.
I goofed around with three propellants and found some interesting things. I loaded about a moderately heaping tablespoon of flour into the base of the mine for testing.
Computer duster is barely worth using. Not very loud, and the flour cloud isn't particulary big.
Propane makes for a decent pop and sprays out the flour well. Funny thing is that the flour blasts out so diffusely that it almost disappears. If you wear black though you can see it quite well. We're sourcing out red chalk to deal with this. Hopefully we (ASCArmoury) can find a nice intensely coloured chalk.
Enter the Madbull regulated CO2 adaptor:
Cute little integrated regulator and fill nozzle. You can dial up the regulated pressure up to 800psi which is about the raw pressure of CO2 at room temperature. Probably pretty dangerous to jam 800psi into a GBB mag though. They're crappy thin walled cast junk metal unlike the alloy steel or aluminum walls on a CO2 bottle expressly designed for 800psi storage. I sense a bit of oversight here since it would also be very dangerous to fill a GBTech grenade/gas reservoir to 800psi too.
Madbull recommends a maximum pressure of 500psi in their landmine so I go right for 500psi and am rewarded with a very sharp bang. Propane exerts about 1/4 the pressure of 500psi so when you're used to 125psi and you hear 500, you're surprised.
When I fill the mine up with flour and fire it off with 500psi CO2, I'm disappointed to find that most of the flour is still stuck in the baseplate. A few more tries and I found the same thing.
I suspect that since liquid CO2 is not injected into the mine as a liquid (regulated down to 500psi) the propellant charge while highly pressurized, doesn't expand to a very large amount of gas. It's damn loud, but it doesn't carry all the flour out of the mine.
I found a very good compromise:
First fill with computer duster or propane. Then top up with 500psi CO2. The final chamber pressure is still 500psi, but you also have liquid propellant to expand into a big cloud of vapor and carry nearly all of the flour out of the mine. Big bang, lots of exhaust. Actually not a bad workaround since propane is also dirt cheap and easy to get into a mine (heh heh).
There is one part of the mine I found annoying though. The black plastic "safety ring" shown in Fig. 3 can be pressed onto the trigger plate stem rather firmly. The tight fit can be difficult to remove without tools (e.g a flat screwdriver). On close inspection I note that the inside of the safety ring is conical (looks like draft on the injection mould. If you put the ring with the wrong side up, it jams on the round standoff in the trigger plate which makes it difficult to remove. I recommend sanding the hole to a larger diameter with a Dremel tool and a mini drum sander. These safety rings should really fall off when you spin off the trigger plate. They shouldn't even lightly press fit.
In the field, I kind of expect that the fill valve may get clogged with mud or dirt. It's probably a good idea to put a piece of tape over the opening in the bottom of the mine to keep dirt and goo out of the valve cavity altogether. Fill your mines before you go onto the field. Slap on a 2" square of packing tape or duck tape to cover the bottom hole (not just the little fill valve) before entering the field. It'll save you from having to lug around gas cans and the mines can be safely carried around with the safety rings installed as they positively block the trigger plate from being compressed against the base.
Finally, filling a mine with a spoon and a bag of flour sucks. Not very tactical to spill visible dumpings of flour wherever you decide to lay land mines. You're probably better off filling a ketchup bottle with a conical tip (restaurant kind of condiment bottle) with powder to poop powder into the base ring.
Cool product which economically addresses the funny need for an airsoft land mine. We're still working to get them up on the retail site (photos etc). They'll be pretty affordable though. Probably around $45-$50 individually with a price break for package deals of 5 units (probably about $40).