I believe maximum carrying weight depends an awful lot on condition and to some extent, the age of the hunter.
There are a LOT of guys at the muzzleloading forum I frequent, who say anything over 7 1/2 to 8 pounds is just too heavy for them.
Aging population or just out of shape shooters?
I still shoot my 9 1/2 pound 14 bore well & shoot my 10 1/2 to 11 1/2 pound air rifles well, too.
Harry Pope once wrote that a man's offhand rifle should weigh 16 pounds and a woman's rifle should weigh 12.
He was referring to Schutzen, 200yard, standing 25 ring "German" target shooting with aperture sighted rifles having palm rests.
I guess proper "weight" depends on the discipline.