Go ahead and leave the extra material on the ball.
It won't affect the accuracy at all.
As was mentioned, the only bad thing that can happen if a oversized ball patch is used is the extra material will end up between the end of the ramrod and the barrel as the patched ball is shoved down the barrel.
Sometimes, if this happens, the patch and the ball will be drug back up off of the powder charge when the ramrod is removed.
No telling how far it might be drug before the patch finally lets go of the ramrod but if it is very far there is a real good chance of the barrel getting damaged by bulging when the gun is fired.
One way of keeping this from happening with an oversized patch is to make sure the extra material is folded over the top of the ball with the end of the ramrod sitting on top of the cloth.
With the cloth folded over the ball, it cannot grab the end of the ramrod.
It won't affect the accuracy at all.
As was mentioned, the only bad thing that can happen if a oversized ball patch is used is the extra material will end up between the end of the ramrod and the barrel as the patched ball is shoved down the barrel.
Sometimes, if this happens, the patch and the ball will be drug back up off of the powder charge when the ramrod is removed.
No telling how far it might be drug before the patch finally lets go of the ramrod but if it is very far there is a real good chance of the barrel getting damaged by bulging when the gun is fired.
One way of keeping this from happening with an oversized patch is to make sure the extra material is folded over the top of the ball with the end of the ramrod sitting on top of the cloth.
With the cloth folded over the ball, it cannot grab the end of the ramrod.