As I noted Hogan everyone will not agree on what is important for terminal ballistics, that is why various options sell. One needs to make an informed decision on a topic such as this, and only use internet advice as one factor. I am recounting my perspective based upon research of published studies, personal experience, and discussions with guides/outfitters who have hosted hundreds of hunters. There is always a never ending step up the ladder to a larger caliber, higher velocity, more power; but the main question is what is ADEQUATE for your max range/purpose? And more importantly how well you can shoot it? I did not say the 308 was my first .choice for elk, or the best choice, but that it and a host of other cartridges are adequate, so the OP would hopefully continue to explore/research options that may provide a better overall fit to his intended uses which we do not know. And I do use a 30-30 for whitetails, where it is adequate; but your example for elk is simply hyperbole.
Hyperbole? As in exaggeration? I dunno. Can kill an elk with almost any rifle or centerfire handgun. For sure a 77gr matchking from a .223rem will kill elk. Kind of depends on your hunting style. Lots of longrange hunters pursue elk. A 500yd shot is mid-range to those guys shooting off a portable bench across canyon(s). Would I choose a .223rem for elk? Assuredly not.
I have tried to rationalize the purchase of a 7mm-08 or .260rem AR-10 upper for many years. At the time, I owned a 6mm International AI upper. This is basically a .01 longer 6mm XC. Great 1000yd or varmint ctg, incidentally. I decided not much reason for me to own an AR-10 in any chambering other than .308win. Same conclusion about AR-15s; stick to 5.56 w/75 or 77gr match bullets. At 500yds the 77gr hits with more energy than a 158gr factory loaded .357mag (from 6" or longer barrel) at 25yds. Hyperbole or Kinetic Energy?
The subject here is switchbarreling with purpose being to enable (presumably longrange) varminting with a 6mm ctg and another ctg specifically for Elk.
Why need 2 different ctgs if one will serve? Could have endorsed the 6.5saum or 6.5/300wsm; but not as versatile as the 6.5x284.
Have a .338-06AI.... a .338/284 would be about identical, yet better for bullet seating flexibilities. But, as I might shoot a moose with greater likelihood than a caribou; mostly I carry & shoot a .338 magnum. Guess that a 6.5x284 and a .338x284 would make a fine combo; yet I have a .260rem palma barrel that I switch on a long action receiver.
Not many cartridges as versatile as the 6.5x284. Wide range of bullets to choose from, some super-high Ballistic Coefficients.
Armalite and others have chambered AR-10s for the .300saum. Olympic has chambered 15s for the 6mm wssm. Then there is the 6.5 Grendel which will surely suffice to take elk. Have seen some 6.5saum chamberings discussed for AR-10 rifles. Pretty affordable to own one AR receiver and a couple of uppers. Almost talked myself into a 6.5 Grendel or 6mm AR on couple of occasions.
Savage 110 series rifles are made for switchbarreling, but I've never owned one. Was going to rechamber the 6mm Intl AI to 6x284, but sanity prevailed.
To really take advantage of the varminting potential of the 6.5x284 with light bullets, you go with the correct twist on your varmint barrel. Your sporter barrel goes 1:8 or 1:7.7 for your selected 140gr bullet. Might find that the sporter barrel will serve for varminting, if you time your shots so as not to overheat. Light varmint contour w/flutes just might enable it all for the OP , if keep inside the 120-142gr bullet range.
