This is something I'm kind of dimly recalling from the FF&S rules and someone will have to confirm it but I think there was a bug with the rifle/cartridge rules where by a large slug with low velocities would have a longer range than a small slug with higher velocities.
I think, say a 15mm round with a 20mm necked cartridge was a way better round than a 5mm round with a 30mm necked cartridge.
Derek Stanley
Sent from my iPhone...