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The Range
Ammo & Reloading
Help with chronograph data
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<blockquote data-quote="tul9033" data-source="post: 1282361" data-attributes="member: 2319"><p>I just chrono'd the MG 124gr JHP out of a G17 with 3.8gr of TG and got an average of 1042 for a 129 PF. My ES was 38 and SD of 14 which is ~3% of my average. I'm satisfied with that.</p><p>I try and give myself a +5 PF boost for any variances.</p><p>The ES and SD are just indicators of how consistent your loads are. </p><p></p><p>Here is a quote from gun tests on SD:</p><p></p><p>Standard deviation tells you how close you can expect the velocity of any shot you fire to be to the average velocity. Statistically, it's been proven that 99.7 percent of rounds fired will fall within three standard deviations above or below the average velocity. 95.4 percent will fall within two standard deviations above or below. And 68 percent will fall within one standard deviation above or below. For example, if our 20 shots generate an average velocity of 1,000 fps with a standard deviation of 10, we can bet the farm that almost every round of that ammo we fire out of that gun (99.7 percent) will fall between 970 and 1,030 fps. Similarly, 95.4 percent will be between 980 and 1,020 fps. And 68 percent will be between 990 and 1,010 fps. Now that's some meaningful data.</p><p></p><p>A small standard deviation is always a sign of ammunition that's been assembled with skill and attention to detail. By the same token, a wide standard deviation can usually be taken as an indictment of quality control. The more consistent the ammunition, the better the odds it will produce the exact same result, both in accuracy and terminally, every tim</p></blockquote><p></p>
[QUOTE="tul9033, post: 1282361, member: 2319"] I just chrono'd the MG 124gr JHP out of a G17 with 3.8gr of TG and got an average of 1042 for a 129 PF. My ES was 38 and SD of 14 which is ~3% of my average. I'm satisfied with that. I try and give myself a +5 PF boost for any variances. The ES and SD are just indicators of how consistent your loads are. Here is a quote from gun tests on SD: Standard deviation tells you how close you can expect the velocity of any shot you fire to be to the average velocity. Statistically, it's been proven that 99.7 percent of rounds fired will fall within three standard deviations above or below the average velocity. 95.4 percent will fall within two standard deviations above or below. And 68 percent will fall within one standard deviation above or below. For example, if our 20 shots generate an average velocity of 1,000 fps with a standard deviation of 10, we can bet the farm that almost every round of that ammo we fire out of that gun (99.7 percent) will fall between 970 and 1,030 fps. Similarly, 95.4 percent will be between 980 and 1,020 fps. And 68 percent will be between 990 and 1,010 fps. Now that's some meaningful data. A small standard deviation is always a sign of ammunition that's been assembled with skill and attention to detail. By the same token, a wide standard deviation can usually be taken as an indictment of quality control. The more consistent the ammunition, the better the odds it will produce the exact same result, both in accuracy and terminally, every tim [/QUOTE]
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