Ball size to bore

[das]

Morning All!!  Since I've been comming to Greybeard I've read and learned quite a bit, but still have a few questions. We have been building cannons and shooting blank loads for 20 years now, but still havent used any projectiles yet. We know that the ones we build at Loose Cannon Gun Works are quite safe to shoot but we dont know what size ball to use. All of our barrels are reamed to 1 1/4" bore and figure we will use about 150 grains of 2f for a lead ball. We normally shoot 650 grains of 2f with tin foil wadding. What I need to know is what size ball I should use. We will wind up making our own mold at our shop from steel. Any sugutsions? Thanks guy's, Steele.

[Double D]

Welcome to our board, nice have you.
I strongly urge you to pick up a copy of the   THE MORE COMPLETE CANNONEER  By M.C. Switlik with selected excerpts from other artillery manuals  It is available for $20 from South Bend Replica's.

You will find a link to South bend listed on our Where to find Blackpowder Cannons and shooting supplies topic at the top of this forum.

For a definition of windage go to our post Blackpowder Mortar and Cannon shooting FAQ's

The correct size projectiles for  1 1/4 bore would be 1.218.  1.25 divided by 40 multiplied by 39.

The correct bore for an  1 1/4 projectile would be 1.282.  1.5 divide by 39 multipled by 40.

You have discovered the dilemma we all have encountered.  What to shoot.  The first thought is to shoot cast lead.  With your  1.25 inch guns you should be okay.  Get bigger than that and shoot lead you could be asking for trouble.   Switlik's book explains everything.

Are you going to join our golf ball mortar contest?

[John N]

Double D,

I'm taking a serious look at one of David's fine cannons. In fact I'd say it's on the top of my SERIOUS wish list.

I've tried to find some of those Fuji aluminum film canisters, but they are becoming scarce. I agree with you that lead balls are probably the way to go. Cannon Mike sells a mold for a 1.226" ball. Is that going to be too big? Can I expect any shrinkage when the ball cools down?

If David decides to make a mold in his shop I hope he can make a few more and offers them for sale!

[Double D]

I would ask the mould maker what size ball the mould drops.  I don't remember wich lead alloy has the greatest shrinkage.  I think i will post the question over on CastBoolit.com and find out.  I couldn't find it right away in my Lyman manual.

You might get away with a ball 1.226 in a 1 1/4 bore.  The windage formula is for full scale muzzloading cannon, but I don't know how mich "play' there is in it.

Some food for thought is that the projectiles used in cannon were usually iron and much less malleable than lead.   Lead being more malleable may be less likely to become an obstruction under pressure.  No science here, just a random thought.

[GGaskill]

Pure lead shrinks the most and is the softest.  My opinion is that if you can get it down the bore without pounding, it's safe to shoot it out.  The windage compensated for fouling, not manufacturing tolerances.

[Double D]

Any projectile that doesn't  freely travel the full length of the clean bore under it's own weight  should be considered unsafe.   That is why the ring guage.

The cannon makers of old specified windage and set the rule at 1/40th of bore diameter.  Although N-SSA doesn't use the old rule they do require the ring quage and require each projectile to pass freely through a ring guage of the same diameter as the bore of the cannon and  2 1/2 calibers long.

[Cat Whisperer]

Pure lead shrinks the most and is the softest.  My opinion is that if you can get it down the bore without pounding, it's safe to shoot it out.  The windage compensated for fouling, not manufacturing tolerances.

DD has a point on rolling the round over several diameters in length, as the irregularity may or may not roll into position where it could interfere.  The issue is one of guaranteeing that there is NO chance of interference, no matter how small the probability.  The consequences are too great to risk.  There are things in life that I practice because once in a while if I don't they'll come around and bite me.

On the other point, tolerances are a relatively new invention, and more clearance did allow for variation in size.  True Eli Whitney did make rifles with interchangeable parts a LONG time ago, but measuring, documenting and controlling the quality of parts (sizes etc.) came along much later.

[GGaskill]

we were discussing bullet or shot moulds, I was expecting reasonably round projectiles, certainly limited in diameter to the mould cavity size.  If you were sand casting iron shot, I would expect a larger size variation and more windage would be useful in allowing the use of more of the shot production, at the cost of less firing efficiency.

Since we aren't firing in the face of an enemy charging with fixed bayonets, we can afford to sort out oversize shot at the time of loading.

[Cat Whisperer]

Agree wholeheartedly.  CW era cast cannon balls weren't nearly as smooth as what can be produced today.

But I would sort before loading - I HAVE stuck a round in the bore.

[Blaster]

When I purchased my little 1/7th scale Dahlgren with a one inch bore from South Bend Replicas ( listed in our suppliers guide ), just a few years ago, they were kind enough to include an extra piece of the seamless liner about 4-inches in length,  the excess piece off the actual liner that they had applied.  I cast lead balls (.960) with a mould that I got from James Mathisrud ( also in our suppliers list ) using wheel weights.  Every single ball that I cast must drop through that piece of seamless ( I consider it my ring gauge ) and I have not had one yet that failed to freely drop through. Never have had one stuck in the bore and I sure don't anticipate that happening.  Blaster (Bob in CO) :-)