I was surprised to go through all those posts and no one mentioned my caliber of choice for a 400 yard shot - .50 BMG.
Maybe that's what the M24 of desertloper was - I'm not familiar with the nomenclature.
Anyway, it's been an interesting thread. Even more interesting to me is how so many get so excited and, well - downright nasty when they have a disagreement with someone else. No wonder so many of our kids have taken to violent video games - they learned it from us!