The rotating barrel was introduced with the Cougar. Remember just about all semi-auto pistols in 9mm up have "locked breech" set ups. Whether it is a Browning linked system (1911) or a linkless design (just about everyone else) the barrel stays locked with the slide for a short distance as the slide moves to the rear. The barrel drops in a conventional system, unlocking and allows extraction and loading of the next round. Beretta simply locks/unlocks without the barrel dropping. THis allows the barrel to be mounted lower in the pistol. THIS is what reduces muzzle flip.
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