Whar iz everybody?

[Cat Whisperer]

Because of the variability in flight of a bullet that is not rotating, it is a problematic issue of determing the most accurate method of loading to produce good accuaracy.

This will be a soon-in-the-future topic when I get a few more golf-ball mortars finished - to examine the effectes of different windages, barrel length, mass of the piece to the effects on accuracy, with golf balls.

Lots of oppinion, I've expressed a few.  I value those that are based on careful experiments, although I'm sure I've expressed a few not-well documented opines.

Consistancy of method has got to be one of the keys.

[John N]

I tried an experiment last night with wad over powder in my coehoen mortar. As I described in another thread http://www.graybeardoutdoors.com/phpbb2/viewtopic.php?t=60478&sid=ea3ab7fb329bb0d539bdbe88e9c9c8f9, the bottom of my concrete filled soda can blew out using a 400gr 1FG load.

This particular mortar has a curved breech creating a sizable airspace between the powder charge and the base of the can. Last night I wadded up a third of a sheet of newspaper to fill this void and theoretically cushion the can from the blast wave. Another can was launched and this time it remained intact.

I'm not drawing any immediate conclusions from this little 2 shot experiment. I could have had a bad can or perhaps there is always going to be a certain failure rate at heavier loads, say 20% or 50% or whatever. A nd yes, the wadding did catch the grass on fire

[Double D]

If the intent of the wad is to seal the breech then this is is a dangerous practice.  It can and  will increase breech pressures.  Sabot were used with round ball to keep them from rolling out of the barrel, but they did not seal the bore.

Keep in mind also wads become secondary missles and as John said can be fire starters.

If you choose to use a wad incorporate it into the foil wrapped charge. Make it from solid material of sufficient thickness that it won't tip in the bore when loaded. Reduce your load before using a wad.

Loose packed or wadded material like newspaper, will also shred upon firing and leave shred particles in the bore which can be difficult to clean out.  They can lay smouldering in the bore and prematurely ignite a charge being loaded.  They can also wedge themselves between the bore wall and  the projectile jamming the projectile in the bore.

What do you do about a 1 inch ball jammed 10 inches down a loaded 20 inch deep bore? If you are just learning about black powder cannons and you don't know any better you cut a real long fuse, stuff it down the vent and fire!    And if your 1 inch bore is drilled down the center of a piece of 4 inch 4140, you and the tube both get lucky and survive.

[John N]

Thanks for the good information. I made sure to mold the wad so it would fit in the round cavity spanning the lipped rounded bottom of the coke can and the central portion of rounded breech face. In other words, none of the wadding was touching the barrel walls. Of course what happened at the moment of firing when the can and wad began their movement in the barrel is an entirely different matter, so your precaution about possible increased pressure should not be ignored.

Here's a picture of the coehorn (the one on the right):



I like your idea of incorporating the wad into the foil wrap powder charge. As far as wads fouling the barrel, this is probably less of an issue with a mortar since it's wide short chamber make cleaning and inspection in the field fairly easy.

And so, what to do with that stuck ball? Why of course you cut the tube in half and make 2 mountain howitzers!

[CAV Trooper]

John,

If you want to add wadding as part of the foil powder charge packet, try using dry peat moss on top of the BP. That's the way we make blank charges for the six pounders at the Castillo de San Marcos and Ft. Matanzas in St. Augustine, FL.

It goes like this: Form the foil powder bag, remove from the mandrel and pour in 10 to 12 oz of cannon grade BP. Then fill the foil with dry peat moss and tamp it down with a wood dowel. Twist the foil closed and the charge is done. The peat moss adds just enough resistance to the burning powder in the barrel to make the boom very deep and resounding.

Since the peat moss is almost a powder to begin with, it virtually vanishes instantly upon exiting the tube. The stuff doesn't burn or leave anything in the tube. Funny thing though, the grass in the moat just below the cannon grows really good.   :grin:

Rock wool used for blow-in insulation in homes works also and is fire retardant. A large quantity of either one is extremely inexpensive.