What is meant by the term "start pressure" in reloading?

The term "start pressure" refers to the amount of pressure necessary to overcome friction within the firearm's chamber and bore when a bullet begins its journey down the barrel. This concept is crucial in reloading, as it helps determine how smoothly and efficiently a bullet will travel through the firearm after being fired.

Understanding start pressure is vital for reloaders, as it has implications for both the performance and safety of the ammunition being created. If the start pressure is too low, it may indicate insufficient powder charge or inadequate bullet seating, potentially leading to inconsistent or unreliable performance. Conversely, if the start pressure is too high, it could be a sign of excessive friction or an inappropriate bullet choice, which can result in dangerous overpressure conditions.

The choices related to igniting the primer, the bullet exiting the barrel, and the pressure required to chamber a cartridge refer to different aspects of ballistics and reload dynamics, but do not specifically define what start pressure signifies. Therefore, the understanding that start pressure directly relates to overcoming friction establishes it as the correct concept in this context.