You really want to use the heavier 100 grain bullets if you're going to hunt deer with your .243. There are quite a number of factory loads out there, and any of them should work well enough if you can place your shots well. If your deer are so big that you are worried about an expanding bullet not penetrating enough, then you should probably be using a larger caliber.

My .243 is very accurate and is quite pleasant to shoot. I have taken a deer with it, but this was a ~75 yard head shot on a doe (she never knew what hit her.) As small as our California blacktail deer are, 120 lbs or so, I am fairly sure that a heart/lung shot would have also been effective. However, lighter bullets usually don't penetrate as deeply as heavier ones, and if you are hunting the really big bucks at longer ranges, you'll want to be really, really sure that you can place your shot exactly where you want it, even with a 100 grain bullet. I would recommend avoiding quartering shots.