firearms may be considered defective if they do not meet the design specifications of self-loading firearms. Primer depth is very important in centerfire ammunition. Most cartridges are assembled with the exposed surface of the primer a specified distance deeper than the base of the cartridge in contact with the bolt face. Primers with insufficient depth may be detonated by the normal amount of firing pin movement as the cartridge is chambered by forward bolt movement. Primer response to impact is a function of the thickness and hardness of the metal cup containing the detonating explosive. Primers intended to respond to the comparatively light firing pin impact of older or smaller manually-loaded firearms may be initiated by the relatively energetic self-loading process necessary to reliably chamber cartridges. Most military ammunition makes use of hard primers unlikely to be detonated by a comparatively light inertial strike. The NATO military alliance uses NATO specific standardization agreement (STANAG)s that define the minimal and maximal allowed primer sensitivity for small arms ammunition. For 5.56×45mm NATO ammunition STANAG 4172, among a considerable number of technical requirements, specifies the permissible primer sensitivity range for 5.56×45mm NATO ammunition. Spring-loaded firing pins may move further forward than expected during the loading process if the restraining spring is broken or weakened by age. As rust, dirt, fouling, or inappropriately viscous lubricants accumulate in the firing pin channel, both free-floating and spring-loaded firing pins may be held in a forward position protruding from the bolt face. While rust prevention is important, wet lubricants can trap carbon and other pollutants from burning propellant, so avoidance of excess lubrication reduces the risk of slam fires from firing pins becoming stuck forward. Anything adhering to the tip of a firing pin or the portion of the bolt face behind the primer may cause unexpectedly heavy primer contact during the self-loading process. The larger priming compound distribution area of rimfire ammunition increases the number of locations where dirt or fouling on the bolt face or in the rim portion of the firearm chamber may deform the cartridge rim enough to function as a firing pin during the self-loading process. Risks Unintended slamfires are dangerous, and recoil may cause shooters to lose control of light firearms with conditions causing sequential slamfires if a normally semi-automatic firearm "goes full-auto" unexpectedly. A single defective cartridge may cause a single slamfire, but a firing pin stuck in a forward