Abstract: In a magazine-fed firearm having its barrel fixed to the frame and having a slide reciprocably mounted to the frame, with resilient means positioned between the slide and the frame urging the slide toward the muzzle, a lever rotatably mounted to the frame releasably engages notches formed in the slide, delaying opening of the breech momentarily after each firing to allow the internal gas pressure to reach a safe level, and retaining the slide with the breech open to signal the firing of the last cartridge. A resiliently biased plunger on the frame restrains the lever against rotation into and out of engagement with the notches.