I think that the ballistics of each have been well tread upon earlier in this thread and it was established that after 325 yards, the 1/4 bore pills loose steam quite a bit faster than the 6mm stuff in the similar weight bullets. For the 90-95% of us that never shoot further than 300 yards, its a none issue. But for the guys who make use of laser range finders and adjustable turrets, a long 6mm bullet has its advantages over a 6.35mm bullet.
