Editing Direct impingement (section)

== Disadvantages ==
The main disadvantage of direct impingement is that the [[breech-loading weapon|breech]] of the firing mechanism becomes fouled more quickly compared to [[Gas-operated reloading#Long-stroke|long]] or [[Gas-operated reloading#Short-stroke fixed|short stroke piston]] systems. This is caused by the operating mechanism's direct exposure to gases from burned cartridge propellant when the firearm cycles. The gases contain vaporized metals, carbon, and impurities in a gaseous state until they [[condense]] on the relatively cooler operating parts. These deposits increase friction on the bolt's camming system, leading to malfunctions. Frequent and thorough cleaning is required to ensure reliability. The amount of fouling depends upon the rifle's design as well as the type of propellant powder used.<ref>{{cite web |url=https://www.silencercentral.com/blog/direct-impingement-vs-piston/ |title=Direct Impingement vs. Gas Piston: Settling the Debate |last=Maddox |first=Brandon |website= |publisher=Silencer Central |accessdate=9 August 2021 }}</ref>

Another disadvantage of direct impingement is that combustion gases heat the bolt and bolt carrier as the firearm operates. This heating causes lubricant to be "burned off". Lack of proper lubrication is the most common cause of weapon malfunctions. These combined factors reduce service life of these parts, reliability, and [[mean time between failures]].<ref>Major Thomas P. Ehrhart Increasing Small Arms Lethality in Afghanistan: Taking Back the Infantry Half-Kilometer. US Army. 2009</ref>