captainbob said:
How can you tell the diffference between a locked breech and blowback?
A locked breech design will normally have a pivoting barrel which will have to "unlock" before the slide can move to the rear.
Actually, in a Browning Style locked breach design, the slide and barrel travel rearward, i.e. Locked together, a short distance, before the unlocking happens in the cycle of firing.
Also, not all locked breach designs have a pivoting barrel design. The Luger, Broomhandle Mauser, Walther P38, Beretta/Taurus 92, CZ52, and Beretta Couger/PX4, all use different mechanisms for achieving the same effect, to name a few.
captainbob said:
A blowback design has a fixed barrel and the slide moves with locking into the barrel mechanism. (Exception: The Luger has a fixed barrel but the toggle provides the locking to the breech).
In the basic Blowback designs there is no mechanical locking, save for the tension of the recoil spring holding the slide in battery.
As for the Luger Pistol (and I own one) it's upper frame and barrel do travel back in the frame a short distance before the toggle unlocks and ejects the spent shell, hence it is a true locked breach design.
As for the PT957, it has not been that popular here, but it certainly deserves a mention. I do know that Taurus added it to it's lineup, the next year after Sig and Winchester/Olin announced it. As to whether it continues on or is replaced by a PT800 model (PT857), will remain to be seen.