I have to disagree on the Benelli 76, as well as the MAB P15 and the Steyr-Hahn.
All are actually locked breech, not delayed blowback. The Benelli is (AFAIK) unique in that it allows a short initial movement of the breechblock to act on the slide, kicking it back and then using its inertia to unlock the breechblock from the frame and continue the cycle. The MAB and Steyr-Hahn (and the Roth-Steyr as well) are locked breech. The barrel is locked to the slide (bolt in the case of the Roth-Steyr) while the barrel turns. The movement allows the pressure to drop before the gun opens. Some will say that the unlocking is taking place while the barrel-breech unit is recoiling, which is true, but is also true of every other locked breech recoil operated pistol I know of, including the M1911, Luger, P.38, M9, etc.
The jury is out to some extent on the Remington 51. It comes very close to a true locked breech, as the breechblock, like the Benelli, is locked until the slide picks it up.
Actually, neither Pedersen (Remington Model 51) or Searle (Savage) designed those actions because there was any real advantage. They had to avoid infringing the Browning patent on a slide combined with the breechblock. It was obvious to everyone that the Colt design was the way to go, but that way was blocked, so other ideas had to be tried. (S&W avoided the slide altogether, as did Davis.)
Jim