load development for mini cannon

[keith44]

I finally have all supplies ready to fire my newest cannon.  .69 cal Traditions "Iron Sides" model cannon.  I have lead balls, dia .680, patches, powder, fuse, and something I've not seen mentioned.  Maybe I missed it, maybe I'm out in left field, but I'm trying something else.  .69 cal works out to slightly smaller than 14 gauge so I ordered some muzzleloading shotgun cushion wads.  I already have some #6 bird shot, but may not use that, I still need to calculate the pressures.  The wad will be used with salute loads until I work out the shot loads.

[keith44]

Oh and yes I know volume of shot should nearly equal volume of powder.  One promising looking load is 75 grains of powder with one oz of shot.  Any thoughts?

[subdjoe]

First remember that the wad will be a projectile.  I've seen a wad from a low based 12 ga. go through both sides of a galvanized trash can from about 10 feet. 

Second, for load development, shotguns often do best with a square load.  Bore of .690, so your shot column should be .690 high.  And an equal volume of powder.  I think that works out to about 7/8 oz. of shot and a volumetric BP load of around 65 grains. So maybe start with about 2/3 of that.

Did it come with any load data? 

[keith44]

Yes, but not for shot or salute loads.  Minimum powder charge 45 grains witha patched .680 lead roundball. Which weigh about 500 grains each.  Max load is 85 grains with the same lead ball.

So the 7/8's oz shot and 65 grain powder (2F) should be perfectly in line with the pressure capabilities of the cannon.

The 1 oz 70 grain load is the service load for old damacus BP 16 gauge (nominal bore of .662)

Your suggestion sounds safer for work ups.

[subdjoe]

Yes, but not for shot or salute loads.  Minimum powder charge 45 grains witha patched .680 lead roundball. Which weigh about 500 grains each.  Max load is 85 grains with the same lead ball.

So the 7/8's oz shot and 65 grain powder (2F) should be perfectly in line with the pressure capabilities of the cannon.

The 1 oz 70 grain load is the service load for old damacus BP 16 gauge (nominal bore of .662)

Your suggestion sounds safer for work ups.

Ah, so you do have some starting load data.   I was being cautious when I suggested using only 2/3 of that approximation of a square load.  Which works out to a 43 grain charge pushing 254 gr. of projectile. 

[mcwoodduck]

A friend of mine used to have a little .50 cal deck gun on his counter and if you were not paying attention when you walked in his shop he would shoot the 5 grains of black powder and flash paper at you.  the powder launched the flash paper ball of flame would be burning its way to you and burn out before it reached you.  About 20 feet away.
It was an attention getter.
A friend of my father's had a signal cannon that had a magnifying glass and a sun dial attached.  I helped him load it once.
It was a small amount of powder and a wad and news print.  When the sun hit the desired time the magnifying glass would light the fuse and BANG - Dinner.