Having some experience with the GPMG in '63 after it was introduced into our ranks in Singapore for further testing, I'd say that removing a pound or two would have been appreciated at that time.
However, the ability of the gun to plonk 98 out of 112 rounds into the 4" bull at 300 yards using short bursts - rapid fire - with open sights, and I've done it, justified the weight to a degree.
I owned a Mannlicher Luxus in .243 at one time. It was so pretty with that satin twist in the barrel. I swapped it for an SSG in the same calibre at a later date. She was ugly but proved much more faithful.
During the time I owned the Luxus there was a big move on removing bolts from rifles in the gun safe, so we complied.
Having stalked a mile round to a 'management' hind and calf one morning, I slipped the rifle into position after pushing the magazine home, and discovered - no bolt -so I left the rifle there under it's slip and stalked back out, drove home and back, stalked back in and the hind was still lying there !
What a plonker ! That was a very unlucky hind.