A cracked pellet won't hurt you or your gun... just be less consistant firing when you shoot it and as a result less accurate. Push your bullet all the way to the powder, to just-touching. Leave no gap. The bullet is supposed to hold the powder tight to the breach.
Leaving an intentional space between the bullet and the charge is a potentially dangerous problem. Best case in that scenario would be that the powder doesn't light, since the powder slides away from the breach plug. If the primer manages to light the powder, the worst case is you get an exploded barrel and a burnt face.
Be safe out there and read your manual. Put some tape on your ram-rod when the bullet is fully inserted. Always push the ram rod to the same spot marked with the tape.