Blank charge weight for 1" bore cannon?

[aaron_l]

I picked up some fg powder and fuse today for my grandfathers salute cannon. Hoping someone on here can help me with a good starting charge. Seen a bunch of conflicting load data. Everything from 160gn for 1" bore (blank charge) to 1oz for 1" bore (blank charge). Found one chart showing 180gn load for unpatched ball with flechette(in pics below). Other info saying use double the powder of that for blank charge. Grandfather passed before he let me know the right charge and my grandmother says she thinks it was 2 tablespoons but she isnt sure and 94 years old. Bore is 1"x 12" , 1/2" trunnions, 1+" thick at the breach and cast iron. Was thinking about trying 300gn's with a small wade of newspaper to start but as the cannon is Irreplaceable, any help would be greatly appreciated.

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[DemonRat71]

Stole this from a Facebook page. Don't treat it as gospel, just a suggestion, always be safe. I would go with the .75 bore diameter just to be safe and work your load up just like reloading any ammo. I saw your remark about the 2 tablespoons and I remembered I had this in my files. I almost got a 1" cannon like the one you have years ago. But decided not to as I would rather have a handgun instead. Again, I will say start on the low side and work your way up. But don't go to high on the charge. Be safe and have fun with it. Hope this helps.
Edit: This is for Fg Powder. Which you have. Any other powder like FFg I would use way less then recommended.

 

[MikeInOr]

I use about 2 tablespoons in my 1 1/2" bore mortar (~4" barrel length).. but would suggest starting out with 1/2 tablespoon and working up. You are aware that you have to pack the powder in and shove something down the bore to keep it compressed? For my mortar I use potatoes. Just wadded up paper packed in there usually doesn't give much of a boom. A 3" long plug of potato usually works well and gives enough resistance for a decent boom.

One 4th of July I had several people over and decided to set off the mortar after dark. I got a really good BOOM but before anyone could react about 30 birds immediately came flying out of the cedar trees that line my driveway and scared the snot out of the crowd as the birds flew over them. Good times!

A good tight plug is key to building up pressure for a good boom. If there isn't enough resistant in the plug you just get a foomp or even just a fizzle. Potatoes turn to dust in my mortar. Even when I turn a plug out of fir on the lathe there isn't enough wood left to put a hole in a piece of cardboard 5 feet away. I have never played with a long barrel canon like yours though.

I always assume that every shot of my bronze mortar will turn it into shrapnel and position it plenty far enough away from me and anything important accordingly.

 

[po18guy]

Your cannon blast must smell like Trump fries.

 

[Stomper]

Since you (I assume) aren't firing a projectile, and what your grandmother said lines up with 2-Tbs, I'd go with 1-Tbs of Fg (course ground for large bore) powder and work it up from there.

You're just trying to make "noise" (I assume).

 

[aaron_l]

I know when he would fire it he would use a sheet of dry newspaper followed by a sheet of damp newspaper. Seen on other forums that damp newspaper is not recommended. In general the connon would recoil up the grass hill(roughly 3 degree slope) around 3-4'. Always made one hell of a BOOM. There seems to be a very large range for a potential charge weight and i cant exactly "look at a primer for pressure signs" like with my other reloads . This is my first time dealing with black powder

 

[aaron_l]

Since you (I assume) aren't firing a projectile, and what your grandmother said lines up with 2-Tbs, I'd go with 1-Tbs of Fg (course ground for large bore) powder and work it up from there.

You're just trying to make "noise" (I assume).

Yes, it never has or will fire any type of projectile. Noise only

 

[Spitpatch]

@MikeInOr is on the right track with balancing charge against the plug media. The good news is, you can't really mess up too suddenly on the high side with plug media (potatoes, wadded newsprint). Excess powder will simply be expelled and/or partially consumed. Tune your charge and your plug media to achieve a good "crack" rather than a "foom".

You CAN mess up suddenly with a projectile. My cannon is 1.25 bore, and with a lead round ball and my "guess" for a powder charge after shooting blanks, I hid behind the corner of the barn after lighting the fuse, gun aimed at a small rusty trash can.

The entire carriage and gun did a back flip, landing on its back like a ruptured beetle. Axle on the carriage broke. Trash can died violently.

Repairs have since been completed. I toned down the load, and buttress with sandbags now when shooting the #10 fishing sinkers.

Be sure to clean thoroughly after each use. Hot soapy water is always best, Formula 409 cuts the blackpowder residue like butter. Dry thoroughly and protect with a good rust preventative (CLP, etc.)

 

[aaron_l]

Thank you all for the suggestions. Between @MikeInOr 1/2 tbs sugestion and @Stomper sugestion of 1tsb, going to try a 180gn charge of fg with dry and moist news paper about 1" long compressed wad and give that a test. Should be pretty close to 3/4 tbs and also lines up with the chart for an unpatched shot. Other then it not doing a backflip or damage in general, what should i be looking for as far as, for lack of a better term "pressure signs"?

 

[aaron_l]

Talked to a great guy at south bend replicas. Super knowledgeable and helpfull. He felt that starting at around 180gn of fg, wrapped with 2 layers of tinfoil packed tight would be a great place to start with 300 to 320 gn being my max ceiling for charge weight. Was told not to use damp newspaper as that was what everyone used to do but it can cause a large pressure spike and people have been hurt. Suggested using a hotdog bun/white bread as a wad to increase the "BOOM" more safely. Absolute wealth of knowledge. He talked to me on the phone for a good 20-30min. So much appreciated to him and all of you here. Antique Artillery Reproductions and Muzzle Loading Cannon Replicas - South Bend Replicas https://search.app/R8tMzAKHKBnkEU886