The 6.5x284 norma and the 284 win are two of the most efficient cartridges on the planet. I had a 6.5×284 norma built on a nesika action. It was one of the most accurate rifles I have ever owned, big fan of this caliber. It along with the 284 dominated the long range competition world for more than a decade.
As to the idea it is not enough for elk???
The European's have been hammering everything on planet earth up to and including elephants with the 6.5×55 for close to 100 years. The 6.5 swed is their 270/3006. The 6.5×284 is an upgrade to the old swed and surpasses the AI version by 50 fps. I have owned all three.
20 years ago I fell in love with the 6.5 swed, not going to lie I am a fan boy and the 6.5×284 is the best of the 6.5's in my opinion. It happened while accompaning a couple guys on a Norwegian Elk hunter, for those who don't know that is a moose on steroids.lol. They both had 6.5 sweds and both got kills. Neither animal took more than a step before they toppled over. They were both shooting 160 gr. SP's @ around 2500 fps, best I remember.
The beauty of the 6.5 is the heavy SD of the bullets. The high SD is why some people don't like shooting a 6.5 for deer. They shoot to much bullet at to close a range and it zips right thru with minimal damage. Hornady's 143 gr. Eldx has a SD of 293 and out of a 26" barrel on a 6.5×284 can be pushed at 2950 fps. It carries more than 1500 ft-lbs out to 550 yards. It should smoke any elk in North America everyday of the week and twice on Sunday.
Ballistically speaking from a long range steel target shooting perspective the 6.5×284 will do everything a 300 WM will do out to about 1600 yrds. I have both and when shooting inside 1250 yards I would much rather shoot the 6.5, though I love my 300.