I have been a VERY big fan of the Sierra 100gr SBT bullet. I use both the federal premium loading and have reloaded to duplicate this load. I have my browning Eurobolt tuned in to this load and it will shoot outrageously small groups at 100 yards. It will shoot well under MOA out to 400 yards which is the farthest I have ever shot it. I always sighted in to be dead on at 25 yards, this puts you +2.75" at 100, about a half inch low at 250, and -4.5" at 300 yards. I have shot several deer with this load out to 300 yards and never had one need a second shot. The farthest I have ever had one travel was about 20 yards and it was a large buck that dressed at 178lbs and was shot at 230 yards. I have had this bullet penetrate both shoulders on several deer. It is the only load that I bother to shoot out of my .243.

Like anything else bullet placement is important with the 243 but I have always found them to be so accurate that it is very easy to place your bullet exactly where you want. I had a neighbor with a 300 RUM shoot several deer in the last couple of years, so far he is 4 for 11 with the RUM. He used to get pretty much everything he shot at back when he hunted with his 270. Does this mean that the 300 RUM is inadequate for whitetails, NO, but he shot his 270 a lot better so it served him better. I have personally not noticed a heck of a lot of difference in killing power from the 243-7mm Rem mag on deer with good broadside shots. Even my 250g loads out of my 35 whelen don't seem to noticably kill any faster or better than my 243. The only advantage with the bigger calibers is that you can take lower percentage shots and still get away with it, and really hard angle shots where it is important to drive the bullet completely thru a deer end to end.