Hi, Abtomat,
There has always been debate as to how much effect the Blish lock had, but the reason it was discontinued was to reduce complexity for volume production in WWII. I haven't weighed bolts, but I don't think the M1/M1A1 bolts were much different in weight from the combined bolt and actuator on the old guns. The Blish lock did have some effect, though, as the later guns had to be strengthened considerably at the back end compared to the older ones.
Hi, Deadin,
The Savage pistols were delayed blowback rather than having a true locked breech. The other guns you mention are actually recoil operated and the barrel and slide remain locked together while the barrel is turning to unlock. The Savages had no real lock; supposedly, the bullet impacting on the rifling tried to turn the barrel the "wrong way" thus delaying or retarding the blowback. I suspect that worked better in theory than it did in practice.
While the Searle system worked OK for the .32 and .380, it just plain was not strong enough for .45. The guns battered themselves to death in the trials, with broken parts all over the place. It is noteworthy that, once the Army trials were over, Savage never even attempted to field a .45 ACP (or even a .38 ACP) on the civilian market.
It is also interesting to examine the reason for the unique Savage system, as well as other unusual systems used by Remington (Pedersen design), Smith & Wesson (Clement design), Davis Warner, and others. Mostly the designers knew full well that their systems were more complex than necessary, with what seem today to be odd features. The reason was that one fellow, named Browning, had patented everything he could think of that might help competitors. One of those patents covered a slide with an integral breechblock, hence those designs used separate breechblocks. Browning even patented the idea of holding grips on with screws, forcing the others to use other, less satisfactory methods.
(Edited to add: Deadin, we both forgot the (in)famous Colt AA2000, the "gun of the future", which is a rotating barrel locked breech. I felt it should be mentioned, but now we can both (thank heaven) go back to forgetting it again.)
Jim