from what I saw the british soldiers NEVER did ANYTHING beyond the 1 (one) mm circle of exposed lead on the bullet tip after filing it down. Otherwise period accounts say that it would oh whats the word... leave bullet jackets inside the barrel at random locations. And even drunken illiterates recruited from british penal colonies realized that was a bad thing.

However I have seen accounts from hatcher talking about having 30-06 cases separate at the neck/shoulder joint and having the case neck act as a second bullet jacket and end up in the target.