Mike: All I can add is that Randy Brooks prefers the 350 vs the 400gr TSX in his 416. I've also read more than one report where the 400gr TSX did some odd things, probably as a result of tumbling due to it's length. I've used the 400gr A Frame myself with good success both in the 400gr 416 Rigby and the 300gr in the 375. I don't think you can go wrong with either but offer the 400gr TSX report as something else to consider. jorge