rifle (n.)
1775, "portable firearm having a spirally grooved bore," used earlier of the grooves themselves (1751), noun use of rifled (pistol), 1680s, from verb meaning "to cut spiral grooves in" (a gun barrel); see rifle (v.2).
rifle (v.1)
"to plunder," early 14c. (implied in rifling), from Old French rifler "strip, filch, plunder, peel off (skin or bark), fleece," literally "to graze, scratch" (12c.), probably from a Germanic source (compare Old English geriflian "to wrinkle," Old High German riffilon "to tear by rubbing," Old Norse rifa "to tear, break"). Related: Rifled; rifling.
rifle (v.2)
"to cut spiral grooves in" (a gun barrel), 1630s, probably from French rifler, from Old French rifler "to scratch or groove" (see rifle (v.1)). Related: Rifled; rifling.