Okay..Since this is a gun writer type forum with some greats here,let's see what some other names have to say about the 6MM/243 on Elk.
JJ Hack
On the surface it would seem that with that many 308 diameter cartridges no wonder I feel this way. Yes but..... It is as likely to work against functionality as well. With that frequency we would likely see equal problems. But that is simply not the case. The 7mm mag compares in killing power nicely with the 30/06, however when it's a 300 mag in the mix there is simply nothing at all similar except recoil and muzzle blast. The 300 mag is a far more lethal cartridge then the 7mm mag. At this point in my career no matter who tries to convince me otherwise, I'm not buying!
In any case there are almost always tracking problems with .243/6mm/.257 diameter bullets. There are close to zero problems with the .338/358/375 diameter bullets.
Wayne Van Zwoll
To destroy vital organs, the bullet must penetrate. To penetrate, it must retain enough mass after mushrooming to overcome the pull of tissue slowing it down. When it gets to the vitals, it must be big enough and heavy enough to make a fatal wound and keep going. Whether it stops just under the far hide or pops through is of academic importance, perhaps relevant to the bullet maker, but certainly dependent on shot angle, distance, velocity and what bones and muscles impede the bullet inside. All that matters to you happens before exit.
For this reason, the .24s are not ideal for elk hunting. In open country at moderate ranges with good presentations, strong 6mm bullets can be deadly. But in the catch-as-catch-can of elk hunting in elk cover, they fail. You need never cripple an elk, no matter what cartridge you use, if you limit your shots to those sure to kill. The trouble with the 6mms is that they require you to pass up shots you could easily make with heavier bullets.
Still, when I can't pick the shot and I must shoot the elk, those delightful, accurate -- and versatile -- 6mms stay in the rack.
Craig Boddington
Those looking for low-recoil efficiency can start with the .243. Since it's the only really popular 6mm, we'll discard all the rest. However, I tend to consider the .243 an "expert's deer cartridge" rather than an ideal beginner's round, and I strongly believe it's best suited for small- to medium-size deer.
Jayco
