The fourth option, the Px4C, is a new thing for Beretta. The "C" stands for "Constant Action." Having seen the overwhelming popularity of the light-stroke double action only (DAO) trigger systems of Sig Sauer (DAK) and Heckler & Koch (LEM), Beretta wisely chose to come up with their own. The Constant Action gives the Px4C only one trigger pull. Shot to shot, it is relatively light and not terribly long, the pull length measuring a very manageable 0.472".
Double-action trigger pull on our test gun averaged 9.96 pounds on my Lyman digital trigger pull gauge, and was consistent from first pressure to the shot without significant “stacking,” or increase in resistance as the trigger came farther back. In single-action mode, the same device showed an average pull weight of 4.84 pounds.