A pierced primer is when the firing pin punches through the wall of the primer cup. Once the primer is pierced, high-pressure and hot gas blast out of the pierced hole and fires back into the firearm which can cause damage to the firing pin, breech face, action, trigger, or any other part of the gun that is in its path. It is essentially a backwards explosion into your firearm. After piercing a primer, you should have your firearm inspected by a qualified gunsmith before firing it again.
Pierced primers can be caused by a single or combination of several factors:
- A “hot” load – a cartridge loaded with more powder than the SAAMI specs, thus increasing the pressure.
- Excessively strong firing pin spring.
- Firing pin too flat or too pointed.
- Thin primer cup (especially when combined with a strong firing pin spring).
- Excessive firing pin protrusion.
The blowback of hot gases can cause damage to the trigger; typically, it will break the sear. This unexpected occurrence would not be covered under our warranty as it is not an issue with the trigger. We will not repair a trigger that experiences a pierced primer because there can be several small fractures throughout the trigger assembly and the critical engagement geometry can be out of spec. TriggerTech will replace a trigger that has experienced a pierced primer through our Damaged Trigger Replacement Program. Please contact TriggerTech for further information.