the ONLY PROBLEM with a .243 when used for deer is useing the wrong bullet. the .243 double duties for both whitetail and varments, but the bullets for both are differant and a thin jacketed varment bullet when used on a deer is going to fragment and not penetrate. but a properly built whitetail bullet will flat anchor those rascals every time. i have abuddy i watch shoot a deer at 150 yrds with a 100 gr corelock on a quartering away shot from a high tree stand. the bullet entered high right side back aways and left bottom front left shoulder/chest area. my son took his first deer ever this year with a .243 (he's 12 and 90 lb) hit it high front right shoulder, the deer was facing head on to him but slitely quartering towards him ever so. bullet went through the shoulder and put a golf ball size holle through the lungs and liver and all the way back the the hams. if shots are kept under 200 yrds you will be fine with a proper constructed bullet. to give you an idea here is the 100 gr .243 bullet compared to a much heavier 150 gr. 30/30 bullet, look at the energy at 100 & 200 yrds.
