Hello,
I have a 16 gauge smoothbore flintlock musket that measures 0.667" at the muzzle with a digital caliper
I had the barrel re-proofed in UK last month and I'm in the process now of doing it all up, work on it is now coming to an end and I am now buying a ball mould.
After placing my order for a mould last night, I woke up this morning having second thoughts about the size I ordered. My Hawken is 50 cal and shoots a patched 490 round ball with a 0.012" patch. It needs a bit of a whack with a ball starter and a little shove with the rod to get going, but then it's OK, accuracy is great 
I intended to use 0.018" pillow ticking for this smoothbore musket as I can get LOADS of it locally and it is consistent. The ball mould seller says:-
"Patches
If you are using a patch, the deduct the thickness of the patch from the mould size. E.g. if you want a .750″ mould and will be using a 15 thou patch, you would want to order a .735″ mould."
"Shrinkage
The next thing to consider is the shrinkage. You can use this simple formula to calculate the cavity diameter: Multiply the ball diameter with 1.005 to get the size of the cavity. This is based on Wheel Weigh alloy with 0.5% shrinkage. For a softer alloy you may increase the factor to 1.007 (0.7%).
These two factors should give you everything to calculate the size mould you need."
So with a bore of 0.667 (16 Gauge) and a patch thickness of 0.018" and times by 1.007 as I'm using soft lead, I got a number of 0.653" and that's what I ordered.
But now I'm thinking I don't really want to be ramming balls down this musket as accuracy is unlikely to as good as the Hawken, so what's the point in hurting my hand for a bad group? I'm only ever going to be shooting 25m Target anyway. I do want to get the best group I can as our club is a performance target club. Also the seller suggested an 0.018" patch was quite thin.
Does anybody know what allowances I should be making for working out what mould I need to buy?
Each mould is £33 ($41) so don't really want to get it wrong.
I'm now thinking of -0.030" x1.007 and adjusting the patch rather than the 0.653 I ordered ????????
The seller is holding back my order until I decide.
Thanks.
