The petronel was a 16th- and 17th-century black-powder muzzle-loading firearm, defined by Robert Barret (Theorike and Practike of Modern Warres, 1598) as a "horsemans peece:. It was the muzzle-loading firearm which developed on the one hand into the pistol and on the other into the carbine. The name (French petrinel or poitrinal) was given to the weapon either because it was fired with the butt resting against the chest (French: poitrine, Latin: pectus) or it was carried slung from a belt across the chest. Petronels may have either matchlock or wheellock mechanisms.
The sclopus was the prototype of the petronel. The petronel is a compromise between the harquebus and the pistol. Early petronels date back to the end of the 14th century, with a crude buttstock. Generally the touch hole is on the right side, and fired by a separate slow match.[1] Sometimes petronels had small hinged plate-covers to protect the priming from moisture.[2] By extension, the term "petronel" came to characterise the type of light cavalry which employed the firearm. The petronel (cavalryman) was used to support the heavy cavalry such as demi-lancers and cuirassiers. The petronel was succeeded by a similarly armed cavalryman called the harquebusier.
Although petronels had fallen out of use in Europe by 1700, similar guns were made in the Middle East until the late 19th century. Afghan horsemen used a gun that was midway between an oversized pistol or a miniature carbine, with a curved buttstock designed to keep the weapon close to the rider's chest.