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Posted: 2/5/2007 7:10:22 AM EDT
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What is the proper method for determing the ROF using a PACT timer? I did some timing of my shorty M-16 and I took the average of the split times and divided them into 60 seconds. i.e. over 20 shots recorded,, the split times were: .56 (I didn't factor this split as it was the first shot) .07 .07 .06 .09 .06 .07 .07 .08 .06 .07 etc. I decided that the average was .07. Therefore, I divded 60 seconds by the split of .07 second and this came out to 857 rounds per minute. Is this a correct method? |
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If you had used the PACT MK4 timer you would have pressed RPM button and read the rate of fire off the display. Put a known number of rounds into the gun say 10 to make math easy. RPM rounds per minute. 10 rnds in 1 second times 60 to make 1 second equal a minute would be 600 rounds in a minute. Since your timer is not designed to respond this fast, it could miss a shot in the string, the more rounds you do the calculation with the more accurate it will be. |
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I posted this over at Uzitalk too, but incase you didn't see it here is the procedure for you to follow: How to measure a machinegun's rate-of-fire with any shot timer. The problem with many shot timers is that they are not so good at resolving very short time intervals. For many subguns, shot timers cannot even reliably count the number of rounds fired because the sound of successive shots can merge together or be confounded by echos. Although split times are a common feature on shot timers, they are not a very reliable number and so extrapolating from them can be unwise. The best way to measure your ROF on any shot timer is as follows: 1) Load your mag up to max capacity (say 30 rounds). Make a note of how many rounds you actually loaded; we'll call this NUMBER_OF_SHOTS. 2) Load and make ready to fire. Set the selector to "auto" (duh). 3) Press the "start" button on your timer. It will beep indicating that the clock is running. 4) Wait a few seconds, then fire off the entire magazine load as a single burst. Its very important to fire the entire mag without interruption. The gun must end up empty, with all the rounds you loaded having been fired. 5) Make a note of the time (in seconds, to two decimal places) to the last shot fired. We'll call this LAST_SHOT_TIME. 6) Using the review function of the shot timer, make a note of the time (in seconds, to two decimal places) of the first shot fired. We'll call this FIRST_SHOT_TIME. 7) Now you can calculate the ROF, in rounds-per-minute, using the following formula: RATE_OF_FIRE = 60 X (NUMBER_OF_SHOTS - 1) / (LAST_SHOT_TIME - FIRST_SHOT_TIME) For example, you load 30 rounds in the mag, the first shot is registered by the shot timer as 2.53 seconds, and the last shot is registered as 4.26 seconds. Your ROF is: 60 x (30-1) / (4.26-2.53) = 1006rpm Hope this helps. |
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