Which process can cause live primers to detonate?

Re-priming involves replacing the primer in a cartridge case, and this process can cause live primers to detonate due to the inherent sensitivity of the primer compound. Primers are designed to ignite when struck. During re-priming, if not done carefully, the primer may be struck or jostled, leading it to detonate accidentally. This risk is especially relevant if the primers are old or have been improperly stored, as the compounds can degrade and become more sensitive over time.

In contrast, the other processes listed—seating bullets, loading powder, and crimping—generally do not directly impact the sensitivity of the primer in the same way. Seating bullets and crimping involve mechanical processes that apply force but do not typically involve striking the primer with direct force that could cause ignition. Loading powder is a less risky process, focused on adding the propellant without affecting the primer’s stability. Hence, re-priming stands out as the most likely scenario for unintentional detonation of live primers.