The leader doesn't need to be precisely shaped to work in bottom load Leicas. Just trim it to about the right shape with sissors in the dark. The problem with short leaders is the film curling and hanging up on the film gate as it is inserted. This can be avoided by slipping a thin sheet of plastic in the film slot, and inserting short leader film behind the plastic. Once the edge of the film is past the film gate, the plastic can be withdrawn, and loading proceeding as normal.