My brother has build a simple speed shooting trainer / timer, which can be used to practice:
1) speed shooting, measuring (with a microphone) the time between 5 shots fired as fast as possible,
2) 25 meter standard pistol,
3) 25 meter sport pistol,
4) Terrain pistol.
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Observe that the edge has been reduced from 1.5 mm to 1.0mm to fit in the enclosure.