Moving Ejection Port

Animating the bolt at the ejection port on every shot, for a realistic MP7 light gun.

Firearms

Moving Ejection Port · Deep Dive

Moving Ejection Port

Realism you can see out of the corner of your eye.

Animating the bolt at the ejection port on every shot, for a realistic MP7 light gun.

Photo: H&K MP7A1, right side (the ejection-port side) by KrisfromGermany

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    Volumes

    1. Vol 1 What the Port Shows: the Real MP7, the Airsoft Copies and the Arcade Where the MP7's ejection port is and what moves behind it on every shot and after the last one, how the gas-blowback airsoft guns reproduce it, what the arcade cabinets learned from moving parts, and what a light gun has to copy
    2. Vol 2 The Numbers: Time, Stroke, Mass, Force and the D16 Sequence How long a port stroke may take, how far it should move, what the moving part weighs and how hard it must be pushed; why the port follows the kick without anyone noticing; the heat it adds; and where a light gun can learn that its magazine is empty
    3. Vol 3 Concept A: the Kick Moves the Port One solenoid for both jobs: the kick mass shaped as the carrier and seen through the port, a lever from the kick to a lighter shuttle, or a shuttle thrown on lost motion; what each costs the kick, how the stops differ front and back, and how a single-coil gun holds open on the last round
    4. Vol 4 Concept B: an Actuator of Its Own Every way of moving the port part separately from the kick, against the clock and the board: a small solenoid, a voice coil, hobby servos, a lead-screw actuator, a gearmotor and cam, shape-memory wire and a latching solenoid, with makers' figures and dated prices; the pick and why; and the second driver stage, the D16 interlock and the hold-open current
    5. Vol 5 Springs, Stops, Noise and Wear Sizing the return spring against the solenoid's pull and the time budget; soft stops at both ends and a residual gap at the coil; where the noise comes from; rods and bushings; PETG, nylon and TPU from their makers' data; why no printed part should flex on every shot; and a life target that can be tested
    6. Vol 6 The Port Cassette for the Printed MP7 A drop-in module behind the ejection port: where it goes in the shell, a dimensioned drawing, the parts list with dated prices, print settings, assembly, starting firmware values, the Analog Discovery Pro bench test with its pass criteria, and the same rails reused for concept A