Mortar Question ....

[1Southpaw]

Progressing slowly on my BB mortar . The Tube diameter is 8-15/16"  ball is 8-9/16 "  The question is ... @ 45 degrees my bowling ball falls/leans  off the powder chamber leaving a gap on one side . Is this going to be a problem ? Does one want the ball seated firmly on the chamber ?  Should I make a ball guide @ 2 points up the tube from powder chamber @center of ball to hold the ball squarely on the chamber ,or is it not to be concerned with .
Thanks

[Cat Whisperer]

Until someone answers with experience this is hypothetical.  Is 'a' better than 'b'?   

BUT YOU can test fire it under both conditions by shooting it as is and then putting a temporary 'positioner' inside fire it and take notes as to any differences.   

I would be cautious about putting something inside to position the ball lest it come loose and act as a wedge.   

[1Southpaw]

Thought about that also . Just wondering what if any difference a small gap on ball setting on chamber would be . Perhaps you are correct , try it , retrofit  if deemed necessary .

This is to be  a fun to shoot it on the 4th of July type project .

Safety is more of a priority than pin point accuracy . 

[Double D]

Tim has said it right Ernie.  Test first and see if it's an issue. 

We had discussion on ways to create spin on round balls for stability...this might be the way.

[Mike Scott]

What happens at 55 or 60 degrees barrel angle?  What about a wrap of tape to bring the ball to the center of the bore?

[1Southpaw]

Still pondering the attachment of powder chamber to base to tube to trunnion.   

Pour'd cannon grade powder in to chamber to measure weight /volume  It holds 3.52  ounces Average .

So according to what I have read that should be a great plenty to send a ball from 150 yards to out of sight. Depending on angle and powder charge weight.   
 

[GGaskill]

... to out of sight.

I don't think it will go that far unless your eyesight is bad or the line of sight is obstructed.

[GH1]

If your concerned about the round not being centerted in the bore perhaps you can use a heavy patch of denim or canvas, kinda like a muzzleloader but bigger.
GH1

[Cat Whisperer]

If your concerned about the round not being centerted in the bore perhaps you can use a heavy patch of denim or canvas, kinda like a muzzleloader but bigger.
GH1

OK in muskets and rifles - but in big bore cannons the rise in pressures can be problematic. 

[Cannoneer]

A definition taken from: "A Naval and Military Technical Dictionary of the French Language" by Colonel Robert Burn, Royal Artillery, published in London, 1870.
Coin - Splinter of wood used in fixing the shell in a mortar.

I'm not saying this manner of centering a projectile over the powder chamber in a mortar should be practiced now, but it was evidently used in the past.

[Double D]

Does that book say what the purpose of fixing a shell in the mortar was?  Centering a smaller  ball?  Generate a slight increase in resistance and increase pressure to adjust range or perhaps light a fuse?

[Cannoneer]

No, this book is just a translating dictionary of military terms, and that particular definition given for coin is all there is. My interpretation of the definition would be that it is describing the remedy for the problem that 1Southpaw opened the topic with; namely, if the shell were resting on the side of the bore because of the angle of the mortar, a shim of wood placed between the wall and the shell would prop the shell up so it was seated more uniformly over the powder chamber (at least that's all I can come up with).