No Shoulder, & it still Fired - Shoulder not needed to fire a primer. Savage Axis 223- TEST- Cut case off behind the shoulder. Install new primer in fired case. Load into rifle using a cleaning rod to keep case head in bolt face & under the extractor. REMOVE CLEANING ROD BEFORE FIRING. Did this 2 times. Both primers fired when the trigger was pulled. 1 case ejected normal, the other did not. Some firearms will need the shoulder, some dont. The extractor must keep the case head from moving forward. Firing pin protrusion can be as much as .055" Its going to reach the primer. If you bulge the neck or shoulder by over crimping, 2 things may happen. 1.A Misfire from a bulge in the neck. This will cause the firing pin strike to be absorbed, as it pushes the neck deeper into the chamber,but only if the cartridge head clearance is large/loose. 2. If the shoulder is bulged from over crimping, the bolt will not close correctly & extraction may be very difficult.