Alex, I tried to answer you question previously, but apparently I used a word that Buds auto parser didn't like and rejected it. I will give you a more simplified answer and hopefully avoid this issue. First off, the P320 is definitely striker fired. As to single (SA)/double (DA) action, let me give you some background. These two terms were coined originally for revolvers. A SA revolver's only releases the hammer to strike the primer. On a DA it rotates, the cylinder, pulls the hammer back and releases it to fire the gun. On the P320 as with vast majority of striker fired pistols the user must pull the slide back and release it to load the first round. When the trigger is pulled the bullet it fired, the slide action then forward and reloads the chamber from the magazine. The firing pin/ striker bar is set in the ready position and when the trigger is pulled the gun fires and the cycle is repeated until the last round is used. At that point most striker fired pistols including the P320 slides are locked back to the rear position. The operator then removes the empty mag and insert a loaded one into the mag well. The operator then must either pull the slide back beyond the locked position or depress the slide release button. The gun is now ready to fire just like the very first time a bullet was manually loaded into the chamber. The P320 is both a SA (first bullet) and DA.

Its a striker fired gun see *** "The P320 Carry offers a smooth, crisp trigger to make any shooter more accurate, an intuitive, 3-point takedown and unmatched modularity to fit any shooter and any situation. Its carry frame is ideal for target shooting and home defense, as well as some concealed carry scenarios. This modular,**** striker-fired pistol features a full-length grip, compact slide, and choice of contrast or SIGLITE Night Sights. Available calibers include 9mm, .357SIG, 40S&W and .45ACP. Safety features include a striker safety, disconnect safety and optional manual safety."

Hi Alex, the P320 is Striker fired according to Sig Sauer : sigsauer.com/store/p320-nitron-carry.html ---- This modular,>>>> striker-fired pistol features a full-length grip, compact slide, and choice of contrast or SIGLITE Night Sights. Available calibers include 9mm, .357SIG, 40S&W and .45ACP. Safety features include a striker safety, disconnect safety and optional manual safety."

Its a striker fired gun see *** "The P320 Carry offers a smooth, crisp trigger to make any shooter more accurate, an intuitive, 3-point takedown and unmatched modularity to fit any shooter and any situation. Its carry frame is ideal for target shooting and home defense, as well as some concealed carry scenarios. This modular,**** striker-fired pistol features a full-length grip, compact slide, and choice of contrast or SIGLITE Night Sights. Available calibers include 9mm, .357SIG, 40S&W and .45ACP. Safety features include a striker safety, disconnect safety and optional manual safety."

Hi Alex, this pistol is a "Striker fired" firearm according to Sig Sauer : sigsauer.com/store/p320-nitron-carry.html