"portable firearm having a barrel or barrels with a spirally grooved bore," by 1775; the word was used earlier of the grooves themselves (1751), and is a noun use from rifled pistol, 1680s, from the verb rifle meaning "to cut spiral grooves in" (a gun barrel); see rifle (v.2).
The spirals impart rotation to the projectile, making its flight more accurate. Rifles "troops armed with rifles," sometimes as part of a unit name, is by 1843. Rifle-range is from 1850 as "distance a rifle-ball will carry" (also, and earlier rifle-shot, 1803); the meaning "place for rifle shooting" is by 1862. Rifle-ball is by 1884; the word continued in use after cylindrical bullets with conical heads replaced round ones.
early 14c., riflen (implied in rifling), "to plunder or pillage" (a place, house, receptacle, bag, etc.), 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 "grapple, seize; pull up, tear, break," hrifsa "rob, pillage").
From mid-14c. as "to rob (someone) in a thorough fashion," especially by searching pockets and clothes. Related: Rifled; rifling.
in gun-making, "to cut spiral grooves in" (the bore of a gun barrel), 1630s, probably from French rifler, from Old French rifler "to scratch or groove" (see rifle (v.1)). Related: Rifled; rifling.