All I can offer at the moment is SAAMI’s glossary definition:

Action, Locked Breech – Any action wherein the breech bolt is locked to the barrel or receiver, through a portion or all of the recoiling motion.

guns that use a locked breech action:

• . . .

 

Footnotes / Sources:

“Glossary ⇒.” Sporting Arms and Ammunition Manufacturers’ Institute. Ed. SAAMI’s Technical Committee. Web. 15-18 Jan. 2011.

 

Question:

• Do you know of a gun that uses a locked breech action that is not on the list?