Paintball BPS meter (com.uzzors2k.BPSmeter) on Google Play
This little app can be used to measure the rate of fire for paintball markers up to 100BPS (balls per second). It may also work for other types of guns/machines provided they produce a distinct sound, but your mileage will vary. Has been tested successfully with real paintball markers, youtube videos of markers being fired, and guns being fired in Battlefield 3. It is assumed this app will function with airsoft markers as well.How to use the app: Simply press start recording and begin firing your marker. The more shots you fire the more accurate the result will be. Once you have fired enough shots (~1 second of shooting) press stop recording, and the app will immediately begin calculating the result. This may take a short duration. The result will be displayed once ready. The recording can also be played back.