Somewhere, in one of my publications on the shelf, was a comparison of rifle calibers from the Remington M40X custom rifle shop. Remington used to ship a target with each 40X showing the capability of the rifle, I think the one I saw was a 308 Win that shot a half a MOA.
The basic trend was the larger the caliber, the larger the group size. I believe that makes sense if the basic rifle platform stays the same weight. The more energy pumped into a structure, the more that structure moves and the vibration mode will change as energy is increased. It is not unusual to see a structure vibrate at least two different ways (modes) as energy input is increased. Whether or not the structure makes it to a third vibration mode depends on a lot of things, because at some energy level the structure comes apart (duh!). Larger calibers obviously pump more energy into a rifle mechanism than smaller calibers, so all other things being equal, you would expect larger movements with the larger calibers. This will result in inaccuracy.
If weight is unlimited, then, I think the heavy calibers will be superior the further you go out. I have not studied this in detail, I don’t know at what distance mass and a reasonable ballistic coefficient start producing better results. Out to 600 yards, heck if I know if bigger is better. I have had buds who were shooting clover leaf groups with 50 Caliber rifles at 300 yards. They claimed they were doing that with ball ammunition. Even the 50 caliber bolt guns are heavy, the Armalite AR50 is 33 pounds. I have heard of some awesome 50 caliber shots by American Snipers, at distances where a lighter bullet would be floating in the wind.
Shooters being human beings, are affected by the muzzle blast and recoil of high horsepower rounds. There are very few people who can shoot flinch free time after time, while all the time being behind something that kicks hard, and is extremely loud. I will tell you, even behind my 22 LR Anschutz M1413, I have to think about flinch, and I have caught myself flinching even though this type of rifle has barely any recoil and is very quite with match ammunition. So what I have seen, is the trend to go with high ballistic, low recoil calibers. The trade off is barrel life.
I was talking to a fellow shooter at the Ben Avery Center, there are so many rifle matches in the area that he prefers to use a 308 Winchester if he can, because the barrel will last a couple of shooting seasons, whereas, the 6.5’s are worn out in one year of competition! Given that once a gunsmith gets to know you, he sits on your rifle, and 6 months is actually a good turnaround for these guys, sometime it goes to a year, you better have more than one sub caliber rifle in the safe, one to shoot, one at the gunsmith, and one ready to use.
Until guided missiles came on the scene, this was the ultimate in large caliber big bore accuracy.
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