slide action
/ˈslʌɪd ˌakʃn/noun
1A sliding motion or action; a mechanism (especially on a firearm) which delivers such a motion or action.
2Originally and chiefly US. A slide-action firearm; = pump-action.
adjective
Originally and chiefly US. Designating a repeating firearm in which a new round is brought from the magazine into the breech by a slide action.
Origin
Mid 19th century; earliest use found in Scientific American. From slide + action.