I would like to say that maybe it would have died in its tracks and maybe not. Last year during deer season one friend shot a buck with his 270 "150 gr bullets" and the deer ran off. As I really enjoy tracking I went to help recover this deer. There was a super blood trail as at times we had blood on both sides of his track. We tracked what seemed forever but finally lost all signs of blood. We think the deer went onto a neighbors farm that we are not allowed on. We know this deer had a fatal wound and that the bullet passed thru but he didn't die in its track. My point being is that at any given time even a mortally wounded animal can just keep on going no matter what it was hit with. As for myself I would not use a 243 for deer but if you want to thats fine by me.