If you ever have a heavy DGR recoil back and your hand on the forearm hits the swivel stud your question will be answered.
Just kidding but that is the reason as far as I know.
Steve
� to deprive the shooter of the thrill of having it rap his knuckle with every shot �o)
� to deprive the quarry of at least a few warning rattles and clunks of muzzles against branches, by hanging the rifle with the muzzle a few inches lower
There's no need to keep the barrel free of this stress, since it's not often or likely that the shooter will be using the sling as a target-shooter would, but merely to carry his rifle afield.
Making the fore-end longer simply to put the front swivel farther forward would add a bit of unnecessary weight to the rifle and shift its balance.
Rifles so rigged were traditionally more often carried with narrow, relatively short carrying straps with fewer laps and folds and less hardware, not the wider and longer (total length) shooting slings. They sure as the dickens didn't go rigged with the Clydesdale harness fitted with cartridge loops, so dear to many modern shooters' sense of necessity.
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Ray Atkinson