The 6.5X55mm won' t fit in your 788 Remington unless it was one of the few that were reportedly made in long action. I know that the 6.5 isn' t technically a long action cartridge, more of an intermediate, but it won' t fit into the magazine of a 788 that was designed for the 243, 7mm-08, 308, etc. Maybe if you seated the bullet really deep, but what' s the point? Too bad you are in Canada or I would be glad to take that puny little 243 off your hands.