Byrna SD unique built-in trigger Pull Pierce Technology
One of the greatest features of the Byrna SD launcher is the pull pierce technology that allows the CO2 cartridge to sit in the launcher unpierced until you pull the trigger, simultaneously piercing the CO2 cartridge and shooting the first round. But this does come at a cost of some velocity on that first round.
So, if you know that you're about to engage someone and have an extra second to respond, you can make sure that first round is at full strength by leaving the launcher you’re on safe and pulling trigger. This will puncture the cartridge and charge the system, meaning that first round, you shoot will pack the most punch.