positions. Box magazines may be integral to the firearm or removable. An internal box, integral box or fixed magazine (also known as a blind box magazine when lacking a floorplate) is built into the firearm and is not easily removable. This type of magazine is found most often on bolt-action rifles. An internal box magazine is usually charged through the action, one round at a time. Military rifles often use stripper clips, a.k.a. chargers, permitting multiple rounds, commonly 5 or 10 at a time, to be loaded in rapid sequence. Some internal box magazines use en bloc clips that are loaded into the magazine with the ammunition and that are ejected from the firearm when empty. A detachable box magazine is a self-contained mechanism capable of being loaded or unloaded while detached from the host firearm. They are attached via a slot in the firearm receiver, usually below the action (BAR, MP 40, AK 47, and M16), to the side of the action, (Sten, FG 42, Johnson LMG, Sterling, and M249) or on top of the action (Madsen machine gun, Bren gun, Owen gun, and P90). When necessary, the magazine can easily be detached from the firearm and replaced by another. This significantly speeds the process of reloading, allowing the operator quick access to ammunition. This type of magazine may be straight or curved, the curve being necessary if the rifle uses rimmed ammunition or ammunition with a tapered case. Detachable box magazines may be metal or plastic. The plastic magazines are sometimes partially transparent so the operator can easily check the remaining ammunition. Box magazines are often affixed to each other with clamps, clips, tape, straps, or built-in studs to facilitate faster reloading: see jungle style. There are, however, exceptions to these rules. The Lee–Enfield rifle had a detachable box magazine only to facilitate cleaning. The Lee–Enfield magazine did open, permitting rapid unloading of the magazine without having to operate the bolt-action repeatedly to unload the magazine. Others, like the Breda Modello 30, had a fixed protruding magazine that resembled a conventional detachable box but was non-detachable. Pistol magazines are often single- or double-stack with center-feed, which may be due to this design being slimmer at the top which can simplify the design of the pistol frame with regards to grip thickness. Some examples of pistols with staggered-feed are the Mauser C96, Stechkin APS, Steyr GB, HK VP70, QSZ-92,