If you take the time and do a little research with an OPENMIND you will see where I am coming from.
It is universally excepted that a 'big' game bullet should have a minimum sectional density (SD) of at least .250. Now with the modern bullet technology, bounded, partitioned, and monolithic hollow point bullets, you can 'fudge' a little on that but not much.
The UPPER limits of the 6mm/.243 is the 100 gr bullet, SD .242!!!!
Compare his to the best hunting bullets in .264, the light one the 129 gr SD is .264, the 140 gr SD is .287. The .277 light one, 130 gr, is the same as a 100gr .243 at .242 (which is why I do not use them, I prefer the 140 gr with a SD of .261 and 150 gr with a SD of .279). The .284/7mm the same goes here the lowest SD here, once again is the same as the HIGHEST in the .243 with the 139 gr coming in with a SD of .246, and the 154 coming in with a SD of .273 and the 160, my preference, with a SD of .287. The .308's are similar with the 165 gr with a SD of .248. The .308 in a 150 only has a SD of .228 but it still way out performs the 100 gr .243 because of it's weight! The 180 in the 308 has a SD of .271.
It boils down to the totality of the circumstances, in this case when you have a light bullet (100 gr), low SD (.242), you get a bullet which has very little 'momentum' (mass x velocity) which results in a lack of the bullets ability to 'penetrate', and the only reason it has fair energy (mass x velocity squared) numbers is it's velocity is high at the muzzle. Because of it's lack of weight (momentum) it MUST be relegated to only PERFECT broadside shots at close to medium ranges on big game.
If you want to shot at longer ranges and/or take quartering shots it is not acceptable if you believe in HUMANLY harvesting a big game animal. Thus it is a MARGINAL 'big game' round!
If I had more time I would address the BC and time of flight (Drift and drop) issues.
If it is possible for you to loose the emotion, myth, and misinformation surrounding the .243 and take an OPENMINDED objective look at the FACTS you will come to he same conclusion I have!
I will take small deer IF you have he discipline to use it within the 'marginal circumstances' it will preform!
Have a nice day, and a MERRY CHRISTMAS!