Because of a higher BC with the heavier bullets. They buck wind better and only shoot a couple inches "less-flat" than the lighter bullet at extreme range.
Sure but now we're talking paper ballistics and they are cited IMO, far too often with BC's and SD's referred to many times as if they have significant relavance, when in field condtions, they really don't...at least when we're talking as small differences between the 140 and 160 grn TSX's. The 160 TSX is a flat base and the 140 is a boat tail and it actually has a higher BC than the 160. I think both should completely penetrate an elk from a broadside shot so I'm thinking the 140 should be a better all around bullet at least in a 7-08 or 280.
Agreed. But BC's are talked about because they do have some real world relevance, namely wind-bucking ability. There's a reason that long range riflemen/the military use heavy-for caliber bullets. You can't really compare a BT bullet with a FB bullet and call that a fair comparison. In equal bullets, the heavier bullet will drift less in the wind. I'm not suggesting that the 140 gr TSX won't penetrate enough, but simply that in a cartridge like the 7RM or STW, the 160 will still shoot plenty flat, buck wind a little better (again in equal bullet designs), and penetrate slightly better on big animals than a lighter bullet.
