Stacking rods allow three rifles to be connected together at the top in order to let them be made into a self standing tripod-affair, to keep them from being laid on the ground in encampment.
Even M1 Garands have a stacking swivel, the "C" shaped thing that looks like a sling swivel.. but isn't. It's for connecting three rifles together to stack them as a tripod muzzle-up.
See:
http://forums.thecmp.org/showthread.php?t=16772
Willie
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