A small metal or plastic device used to aid in the loading of ammunition cartridges into a magazine. Generally used for rifle magazines, a stripper clip is a long, thin metallic strip which attaches to the base of the cartridges, organizing them into a line or stack. It may be slightly curved. The stack is then placed at the magazine entry, and the rounds are 'stripped' off the clip, pushed into the magazine itself; or the clip is inserted into the magazine and then pulled out, leaving the rounds inside. The magazine in question might be either a built-in magazine such as those found on the M1 Garand or Lee Rifle, or a removable box magazine such as those used on the AR-15 or other modern rifles.
The stripper clip is used to hasten the process of reloading the magazine. Since the stripper clip aligns the rounds properly, all that is required from the user is force to move them into the magazine, past the retainer and up against the magazine follower. Especially in modern rifles, whose magazines can hold 30 or more rounds, this is a time-saver. In addition, as a magazine nears full and its spring becomes very tightly compressed, the force required to insert rounds goes up noticeably. it can be difficult to apply enough force to insert new cartridges while keeping them at the right alignment to pass the magazine lip; the stripper clip relieves the user of having to align the rounds.
Some clips are loaded into the rifle magazine with the rounds, and remain in the magazine, either being ejected or falling through the bottom when the magazine empties. These are not stripper clips, as the user does not strip the rounds off, the weapon's action does.