Blish lock

He developed a working model that used a simple wedge as the delay mechanism, and was eventually assigned U.S. patent 1,131,319 on March 9, 1915.

Despite the patent and use of the system in the Thompson submachine gun, the Blish principle found little scientific backing.

[1] In the simplified WWII M1 Thompson re-design, the Blish locking block was removed without substantial change to the gun's function with the .45 ACP cartridge.

The Blish principle did provide delay in the Thompson prototypes using the .45 Remington–Thompson and .30 Carbine cartridges which generate higher pressure than the .45 ACP, a pistol round.

The autorifles developed by Thompson, Colt, and BSA in the 1920s using the Blish principle never went beyond the prototype or trial stage.

Blish patent
Thompson M1928A1 bolt group with an "H" type Blish-lock piece
The Thompson Autorifle Model 1923 (top, upright) chambered in 30-06 and SMG Model of 1921 (bottom, inverted) are both examples of firearms that used the Blish lock