To even bother with copper, brass, tin or any material of lesser density than lead is ridiculous. Lead itself is just barely dense enough to make a round ball effective to 100 yards. Copper balls would maybe make a 25 yard load, if you could keep them on target, which I doubt. As I explained before, lead needs to be soft to be shootable. To obtain accuracy with a patched round ball it needs to be engraved by the lands and soft enough to be started and rammed downbore by hand, only pure lead is soft enough to shoot accurately from a muzzleloading rifle.
If there were any "practical" alternative to lead, soft, dense, affordable and easily formed, it would have been used in shotshells for the past thirty years.
Actually this is a miss conception a round ball is not engraved by the lands . It never touches the lands or groves . if you remove the patch even a solid Granite ball , if of the same size will simply roll down you barrel . you cant get any easier loading then that . what plays the biggest part in dificulty in loading is the thickness and material of your patch . its a give and take issue concerning them . to thick and its hard to load even soft lead . to thin and they wont seal or they burn through .
If you mike your bore , you will find that the ball is normally 5 to 10 thousandths under bore size .
The patch is what actually fills the rifling . The softer the lead the better the patch grips. the rifling this imparting spin to the ball as it goes down the bore .
To hard a ball and the patch will slip around the ball . Thus the spin is not completely imparted to the ball .
Now of course this changes if you are shooting an un patched round ball of true bore diameter. These were call dumb dumbs and were either hammered to a spherical shape prior to loading or the shape was caused by the loading process . These are mostly found in very limited an rear historical references
While I would agree that lead is still the best for the application , if an when these laws start to spread then we have to find another substitute.
Part of finding that is learning how to get that to work like we want it .
The problem with brass is that its so hard you cant get the patch to hold the ball .
Now mind you for a smooth bore , it actually shoots very well to well beyond the distances your thinking .
Now with a rifle , what I found was that if the brass and copper ball was imprinted “ same goes for some alloys , used for wheel weights “. The patch could grab it and hold it . Thus accuracy wasn’t lost once a load was worked up for it . Basically if you cant scratch the ball with you thumb nail , its best to imprint it
Now expansion was about 0 when fired through a simi solid target .
To imprint the brass what we would do is lay the ball on a file . Using a board we would press down on the ball and slowly roll it across the file . What was left was checkered ring around the ball . The ball is then loaded with this imprinting facing the patch .
As to loading , I found the brass balls loaded no harder in my rifle then a lead ball did
Now that was using just a standard Red or yellow brass and copper that you can get at any plumbing store . Actually the yellow brass was from empty cartridge casings that I picked up while at the range .
But again this isn’t to say that any of this is better then lead . Its not . Lead gives you the best of all possible out comes .. Its easy and cheep to cast even the most in experienced person can learn to cast it quickly to a reasonable result . It doesn’t take any special equipment to cast .
It IMO is truly the best hands down
However again if these laws start to spread , we have to find other material to use and then LEARN how to make them work .
What we will find is that they will work and work well .
Anybody remember the Hornady copper jacketed round ball that they used to market ?
Part of the problem I found with them is they would slip the patch and thus accuracy at distance suffered . But if you imprinted them , they shot just as good as any lead ball