I guess this is true for all 'overbore' cartridges, and should be kept in mind by us modern folk for whom 22" is a longish barrel. One could end up just burning up lots of expensive powder, not to mention the barrel, just to illuminate the hill or heat up the moderator.
Just had to find my notes on this which date from 2006 - 2007.
The rifle was a 24" Rem M700 bought very cheap by a target-shooting member. At that time 6.5mm Match bullets were scarce, and all expanding bullets were Section 5 restricted. It seemed like an interesting project to play with an unobtainable calibre in somebody else's rifle. I was already loading for my 6.5x55 so had all the bits & dies needed for .264 WM.
Standard testing routine on the club range, with a ladder load of 52.0 - 56.0* IMR 4831 (140gr) & 55.0 - 59.0* (120gr) of the same, in necked-down Remington 7mm RM cases clocked over an Oehler 33.
It was something of a flame-thrower, and velocities were disappointing at max* of 3000 (120gr) and 2860 (140gr). I had slower powders in Norma 204 and MRP back then, but thought they might have made the muzzle blast and flash worse. It wasn't as flexible to load for as the 7mm RM, which I've always seen as an ultra .270.
The results weren't much better than my .270 in ME terms.
Folk might be interested in seeing the expansion. ratio (ER) of chamber to bore (24" barrel) for various cartridges from Guns Review:-
.300 WM (5.8), 7mm RM (5.3), .264 WM (4.75), .270 (6.35), .243 (6.15) - all compared to the much more efficient .308 (9.25).