Exactly...

Not sure if the exact chamber pressure on a D12-0 but probly in the neighborhood of 80-100 psi... As the motor burns the propellant slug holds this pressure in the casing between the burning propellant slug back face and the nozzle inner end and nozzle hole, which is constantly expelling gas to create thrust. When the slug of propellant burns thinner and thinner till it's a disk, at some point it shatters from the chamber pressure behind it, instantly creating another much larger outlet for the pressurized flaming gas, that being the front of the motor case. This blows burning chunks of BP from the shattered disk forward, igniting the second stage. The chunks of burning propellant move slower than the expanding hot gas, which arrives first and can blow the stages apart before the burning particles ignite the upper stage, hence "pass-port" or other gas vent designs, or taping the motors together so they hold together until the upper stage motor repressurizes the booster motor case between the two nozzles, at which point the tape becomes the weak link and ruptures, allowing the pressure to blow the stages apart...

The problem is the volume of gas and speed it's delivered is smaller than that from a fast-burning BP ejection charge... Might not be enough to elect the laundry, especially from a large tube with large volume...

That and ZERO delay between thrust and "ejection"...

Later! OL J R

Better late than never... Posting as I read the thread rather than read all the way thru the post...

Later! OL J R

My concern on the D12-0 would be charring of the relatively thin stuffer tube and over coming the base drag of the transition while in flight.I personally wouldn't try it on a dare.