I had a H&K VP70Z in 9mm that was blow back, no gas, fixed barrel, only problem was they are double action only. They are 18 shot plastic stock/frame sights on slide, unsure when they were first made but the one had, I bought second hand in the mid to late 1980's.

The Japanese had an automatic rifle and/or LMG toward the end of WWII in 6.5X50mm that was a straight blowback design. People who tested it said the "ejection was very vigorous", empty brass flying out the side was almost as dangerous as the bullet.

If I could give some counter examples:
1) My heavy M1903 .380 pistol shoots 357 mag loads, 8.5 gr Power Pistol, 158 gr XTP, 1187 fps, and it is a blow back.
2) My Kel-Tec P-3AT is a 6 ounce .380 pistol, that can barely shoot 9mm loads and it is a locked breech.

I have done some calculations on blow backs in the past, and it seems the bolt mass gets too high or the spring force gets too high when trying to support a powerful cartridge. Maybe the gun designers are being fooled by the same calculations.

link to my old calculations

Astra 400 and 600 autoloading pistols were of blow back design in 9mm Largo and 9mm Parabellum. They worked well enough but had a strange grip angle. Most use locking mechanisms to make the gun lighter than it would be as a blow back. .45 ACP can be blow back operated as it is in the M3. Be a bit on the heavy side I'd expect with a very strong spring.

Read "Hatcher's Notebook". It has some very clear pro/con discussions of the various automatic designs. The Beretta design is really a Benelli design and there was an automatic pistol made using the Benelli delayed blowback design. There is an article in an old "Gun Digest" on the pistol.

The bottom line is, before you get to thinking you are John Browning reincarnate, do some careful homework.

Competition shooting (pistol or rifle) is about 99% talent and 1% equipment...and if there is a "better mouse trap" out there you can be assured it will start showing up on the firing line real quick if someone wins a match using it.

Rick

Why do we have the complicated locking mechanisms on most semi-auto pistols? From a cost and accuracy perspective, it seems like a heavy slide with a straight bolw back design is the way to go. In this manner, the bbl can be fixed and part of the frame. For competition, the bbl can be extended and a tall front sight directly attached. The rear sight can be mounted on the frame. In this manner the bbl and sites are one piece, and far more stable than using lock lugs on the bbl.