You aren't preaching to the choir...okay maybe you are, but they need it every once in a while. So I will preach to them a bit also.
This is just the way i do it ,taught by a good fellow named Gun smoke.
It appears you had a good conservative tutor who practiced good technique and safe procedure. Consider your self lucky to know such a person. Most people come to cannon shooting and try to apply muzzleloading small arms techniques and don't get the guidance you got.
For those who aren't as fortunate as you to have a good mentor they would do well to acquire a copy of
THE MORE COMPLETE CANNONEER By M.C. Switlik with selected excerpts from other artillery manuals. Good safe cannon shooting information can be found in this book! The book can be ordered from these two suppliers.
The Complete Cannoneer from Matt Switlikand
South Bend Replica Most of your charges are better if they are in foil. Find a PVC collar about the size of your bore.
Cut a piece of foil to fit into the collar, shoving it in with a wooden dowel or hammer handle.
Steal the wife's measuring cups and find one that is one ounce.
Remember BP is measured by volume not weight.
Get your Cannon powder, and measure it out to one ounce per inch of bore ,this does not have to be exact ,just accurate.
Pour it into the foil until you get your charge,then fold it over sealing it,mark on it the size of the charge with a sharpie.
Store in an old ammo can, they work well for this.
Couple of things. I am going to assume a far greater experience here than you on this subject. Marriage--41 years....never ever ever, borrow or steal any of the wife's tools. If you have any semblance of common sense, her measuring devices and cook stove (her toy's) are off limits. This has nothing to do with cannon shooting. It's a basic marital survival technique...so buy your own tools. Don't even ask me how I know!!!
Weighing/measuring powder charges. You are partiality correct. To start you should weigh the charge on a scale and then set your volume measure to hold that volume of powder. Never rely on the markings of powder measure. For my 1 inch gun I have a 50 BMG case cut down to hold my charge. I determined the correct weight charge for my gun and poured that weight of Cannon grade in the case then cut the case down. One thing that should be avoided is using a small powder measure and throwing multiple charges to get your charge. Doing this, your charge will settle and compress. The volume will weigh differently every time. You want a measure that will throw the correct charge in one throw.
Couple years ago, The Artilleryman gave us permission to post a copy of their article on making cartridges. It's right here.
Making Cannon CartridgesAs I said your loads are very conservative. That's good and safe, especially since you are using heavy lead projectiles that will raise pressures.
Both N-SSA and AAA allow larger max charges and they are conservative.
Safe Loads and Cannon plans . But always remember those are maximum loads. By limiting yourself to 1 oz per inch you built in an additional safety cushion. I sure you noted Matt Switlik load recommendation in his book to start ridiculously low. You prove the worthiness of that statement with your success.
Projectiles. several people out there make molds ,casting molds. I like mine 1/32 less than the cannon bore,in this i am talking smooth bore which i prefer,and they will cut them to that amount.
Casting: I use wheel weights,a large melting pot is needed,a propane heater ,and a 5 gal.bucket of water with an old towel in the bottom filled with water.
Heat your mold up on the propane heater,melt your lead,and the object is keep the mold hot.pour the lead into the mold ,wait a second,then open the mold into the bucket allowing the ball to fall out into the water.
You will get it down ,then you know just what to do,and you have a perfect ball.
Some guys are now using cement,this works fine but you have got to let the Cement cure. so you get one ball a day.
Some use cans,i use cans for reasons i will not go into,they work much better for that.
Well the rule of thumb for windage is 1/40 of bore diameter. It's a rule of thumb, not a law and can be worked with. I am relieved to see you are using a low powder charge of Cannon grade with tight lead balls and patches. That helps to keep the pressure down. Again you will find Switlik saying avoid lead and patches in cannons. They are recipes for increasing pressure. It always desirable to try and duplicate the weight of the original projectiles.
Your 3 Inch Ordnance rifle of course used shell and bolt and not round ball. But I do understand using Round ball as an expedient. I dearly would love to see some one post on making bolts or shells. A 3 inch WW lead ball should weigh around 5.6 pounds. This is lighter than the original.
George's Spherical Shot Weight Calculator A 3 inch Iron ball would weigh 3.6 lbs and one of zinc would go 3.4 lbs. Have you considered casting you ball of zinc?
For your Napoleon, Zinc balls would be great. The original Napoleon’s were 12 PD or 4.62 bore and shot a ball 4.52 in. That is almost exactly 1/40 windage. Your 3.5 inch bore gun using 1/40 windage(3.5/40 x 39=3.4125) should use 3.4 inch ball that weighs 8.23 lbs in WW, or 5.3 lbs in iron or 5.0 in zinc. Using the lighter ball of the correct diameter on a wooden sabot should give you good accuracy with less equipment stress from recoil due to the higher pressure.
Upon loading you slide the foil packet into the bore seating it,then take your ball and i wrap it in an industrial paper towel,really.
Slide it in and packing isn't necessary ,just seat it,and you are good to go,the towel seems to improve accuracy.
Use a brass vent pick,Pierce the foil,and use your Fuse or friction primer.
I know some have already gone over this, but i got a PM asking me to post it. it is just the way i do it.
Instead of patching the ball have you tried a sabot? It would do wonders to reducing pressure and lessening the chances of a hang up. Several fellows here have posted on this subject. I think Evil Dog wrote a series of post showing how to make them. They are high on my list of projects when I get home this spring.
