Archers carried specialist arrows, bodkins with needle-pointed heads to punch through mail links, or armour-piercing heads perhaps tipped with steel to penetrate steel plates. Tests have shown that the spin of the arrow in flight enables the head, striking at right angles, to drill a hole into armour plate. The range at which an arrow was shot, as well as whether iron- or steel-tipped heads were used, would determine its potency. Most surviving oxidized red bodkins seem to be of iron, which tests suggest curl up when they strike plate. If they struck mail they would burst the rings apart as they went through, a serious threat to anyone in plate armour, exposing a mail gusset, for example, at the armpit. Crossbows were equally powerful although they did not employ bodkins. Handguns were also appearing in armies in the 15th century, though not in any great number at this period.