You don't need a blood trail until the day you need one. On that day it's better to have one. No experience with 6.5s. Know beyond doubt the .22 and .24 CFs do not reliably produce blood trails. Good killers? Yes.
Context is important. Guy shooting in open cover able to pick plexus shots or, at least, watch a death sprint over just the first 50-100 yds is not in the same galaxy with a guy sitting on a stump within a dense Maine cedar swamp....most likely having a 1/3 chance at a deer bounding past during an four week season. Yes, those are the numbers and yes, there's a reason dogs find many each year. Have that t-shirt and DVD.
