Canadianammo+OMEN XR=Rifled barrel.
Thanks to CJ81499 for finding this out. Well, he managed to make my gun shoot like it had a rifled barrel (FYI, a rifled barrel spins the ammo horizontally for more areodynamics), so now I have the first knex gun with a rifled barrel that shoots well. www.instructables.com/id/SWVUCGGG2HE1A1C/
More details in the link.