Disproving the myth of "Air Gap is dangerous" for Black Powder Cartridges

[hawg]

OK, black without an airspace burns at the same rate from back to front. When there's an air gap it burns all at once. It's an explosion instead of a gradual burn. There's a huge energy spike.

 

[RWMC]

Thank you for the excellent information that you provided in post. I happened to own a Frankford arsenal .45 caliber 4 cavity Roundball mould, like what you mentioned, and now I am going to have to try this! Good info sleepysquirrel2.

My Frankford arsenal round ball mould measures .455.

 

[whughett]

OK, black without an airspace burns at the same rate from back to front. When there's an air gap it burns all at once. It's an explosion instead of a gradual burn. There's a huge energy spike.

That just don’t sound right to me. Black is classified as an explosive. Explosives release all their emery at one as Exploding. smokeless burns at a controlled rate with the pressure spiking then dropping off.
The most plausible explanation I heard is the explosion of black powder has a hydraulic effect on the air column. The air compresses and acts as an obstruction would as it’s ahead of the pressure front created by the black powder charge exploding.

 

[hawg]

Maybe you're right but that's my take on it.

 

[Malachi Leviticus Blue]

...The most plausible explanation I heard is the explosion of black powder has a hydraulic effect on the air column. The air compresses and acts as an obstruction would as it’s ahead of the pressure front created by the black powder charge exploding.

Not arguing, just pointing out that an air gap would be pneumatic not hydraulic.
The technical difference being air is compressible and hydraulic fluids are not.

Folks familiar with pneumatic control systems will be aware that under certain seemingly benign conditions, air pressure can end up building up much higher in a portion of the system than that of the rest of the system, and/or it was intended to be causing movements to occur with much more force than expected.

 

[tightgroup tiger]

That just don’t sound right to me. Black is classified as an explosive. Explosives release all their emery at one as Exploding.

It is an explosive, but it's a low explosive vs a high explosive or we wouldn't be able to buy it. it still has a controlled burn rate when loaded properly.
If it didn't there wouldn't be any reason to have different grind sizes for different calibers. Single F being the slowest burn for the largest calibers.
If it were high explosive, if wouldn't make any difference what the grind size was it would just explode like C4.

 

[Paul R Zartman]

It is an explosive, but it's a low explosive vs a high explosive or we wouldn't be able to buy it. it still has a controlled burn rate when loaded properly.
If it didn't there wouldn't be any reason to have different grind sizes for different calibers. Single F being the slowest burn for the largest calibers.
If it were high explosive, if wouldn't make any difference what the grind size was it would just explode like C4.

I learn something I forgot every day here on THR...

 

[Black cloud]

Maybe try 60 grains of 3f in the 45-90 case?

Hell yeah