flammable contaminants or additions, the temperature rise associated with the compression may ignite the mixture in a similar way to fuel in a diesel engine. This adds to the energy of the system, some of which is transferred to the pellet as increased velocity. Owing to the relatively small muzzle energy of air rifles compared to the stored chemical energy in oil, dieseling can make a substantial difference to the velocity of the pellet. While generally an unwanted phenomenon due to the effect on accuracy and also potential damage to rifle or sight, it is sometimes deliberately engineered by oiling the pellet or chamber, in order to increase the power of the weapon. This is normally done as a stunt or in experimentation - the tiny amounts of oil involved makes consistency impractical, with consequent substantial adverse effect on accuracy. References DIESELING IN SPARK-IGNITION ENGINES External links Engine run-on, Dieseling Car dieseling after shut-off — Car Talk — May 2017 What causes dieseling or "after-running" What is airgun dieseling and how dangerous is it really Engine problems