For the record IMHO, 6.5 is not a selection I would make for elk. You can kill anything with shot placement and a 22 but it does not allow for margins of error. For elk I would step up to a 30 cal and a proven hunting bullet but that’s just my opinion.
So would you rule out the even larger moose as well? Males average 840-1870lbs.
Because nobody got the memo in Scandinavia since the late 1800s that their 6.5x55 Mausers wouldn’t work on those, and most of those rifles were pre-WWII steel alloy that didn’t take modern pressures, so mv was pretty moderate compared to a 6.5CM or .260 Rem.
You’re looking at around 2380fps with a 156grl, and 2625fps with a 140gr from a 29” barrel at those lower chamber pressures.
They’ve been stacking moose like the plague hit them for well over 120 years. Every year in Sweden, they kill an average of 100,000 (not a typo) moose. 60,000 in Finland and 40,000 in Norway.
Not only do the old, lower pressure 6.5s work well on moose, but they and the 7mm cartridges have average shorter travel distance from the shot before they go down, at least according to a Scandinavian moose-hunting survey with over 14,000 sample responses from hunters. .30 caliber cartridges averaged higher travel distances from the shot compared to 6.5mm and 7mm.
I think that’s more of a factor of lower recoil building confidence, which helps tremendously with shot placement.
Better shot placement = faster kills.
When you break the shot, lose sight picture, and have significant muzzle blast, it’s hard to see what happened.
The only argument for .308 for me right now is SHTF ammo commonality/availability.