fffG Black Powder Question

[Little Guy]

I see that there are beer can mortars that the manufacturer says they shoot cement filled beer cans using ffg or fffg BP a distance of 1/2 miles or so. See web sight below.

www.cannon-mania.com/mortars.htm

Is this safe?  I am reading every where that i shouldn't use aything finer than ffg.  
Here is a print of my mortar.  Feel free to comment on the design.


Thanks:
LG

[John N]

I have one of these mortars but have only used Fg in mine. I found that 350 grains of Fg was the upper limit for concrete or cement filled beer cans. Any more powder and the cans break up.  If they got a half mile  with 350 grains of FFFg, it was probably a surviving chunk of concrete and not an intact beer can.

[Double D]

Is this safe?  Thanks:
LG

In a word no!!!

Can you get away with it, probably. Why take the chance, what's the purpose?

For some reason you drawing won't open for me big enought to see any detail.  

Review the safety rules for for firing black powder cannons found at this post: Safe Loads and Cannon plans[/color]

Compute your maximum load based on the diameter of the powder chamber in your mortar. Don't use powder smaller than FG for a Tin can mortar.

[Cat Whisperer]

Tripple F is FAST burning powder (read 'high pressure').

The barrel is right much short, as most mortars are; agree that 1/2 mile range is extremely optimistic!

Even with a 2' long tube a half mile might be achievable, but only with a handfull of powder (and then the slower powders would be better with the longer tube).

[Little Guy]

Double D
Lets try a new picture of the mortar.


Can any one tell me what the Dia. bore is of there beer can mortar.  Mine is at 2.625" and a can measures about 2.610".  Just wondering if i have enough clerance for a soda can.

[Little Guy]

I think this is a larger picture.

[Double D]

You can increase the diameter of the powder chamber to a max of 1.4 inch. You could also increases its depth until the bottom is with in 1.4 inches of the trunnion cut.