I used to clean Marlin tube magazine's with a cleaning rod.
With mag tube removed (empty) I used a cleaning rod to run the cartridge follower down and compress the magazine spring, brass tubes were bad at gumming upwith powder residue and incompatable lubricants that would gum up over time.
Especially new guns treated with a anti-corrosion storage lube that set's up like varnish over time.
Assumption is the mother of all screw-ups.
The factory most likely tested the weapons function before a final wipe and into shipping container.
I knew a guy that bought a brand new Chinese made SKS and out of the box the cosmoline had seized the short spring loaded gas piston extension located inside the rear sight base.
It was a brand new semi-automatic/single shot straight pull rifle till that gas piston extension was freed.
Storage oil/cosmoline can almost epoxy moving parts together.