ultrablue Posted August 30, 2011 Share Posted August 30, 2011 How many rounds should be fired for a chrono session? Link to comment Share on other sites More sharing options...
Dwain C. Baer Posted August 30, 2011 Share Posted August 30, 2011 How many rounds should be fired for a chrono session? At matches usually three to four rounds. However, if you're testing reloads, perhaps one or two magazines worth. Link to comment Share on other sites More sharing options...
bbbean Posted August 30, 2011 Share Posted August 30, 2011 Test enough ammo to trust your numbers. If I'm working up a new load, I need at least two runs of 20 rounds that make power factor with a safe margin. This means that the slowest 7 rounds make power factor, and the run of 20 is at least 1.5 standard deviations above 165. If I'm checking a known load before a major, one run of 20 will do, assuming it checks out. Link to comment Share on other sites More sharing options...
KyroWebs Posted August 30, 2011 Share Posted August 30, 2011 (edited) If I am just starting to work a load up I'll do 5 or 6 just to see approximately where I'm at. Once I get to my desired velocity I'll do 30 rounds. If my avg velocity - 3SD will give me PF above 167(major) or 127(minor) I am happy. Edited August 30, 2011 by KyroWebs Link to comment Share on other sites More sharing options...
Dwain C. Baer Posted August 30, 2011 Share Posted August 30, 2011 If I am just starting to work a load up I'll do 5 or 6 just to see approximately where I'm at. Once I get to my desired velocity I'll do 30 rounds. If my avg velocity - 3SD will give me PF above 167(major) or 127(minor) I am happy. Sounds like a good plan... Link to comment Share on other sites More sharing options...
ultrablue Posted August 30, 2011 Author Share Posted August 30, 2011 Thanks folks. Sounds like between 20 and 30 for a good evaluation of PF. Link to comment Share on other sites More sharing options...
RePete Posted August 31, 2011 Share Posted August 31, 2011 I use 10rds for pistol and 5 for rifle. Link to comment Share on other sites More sharing options...
blueeyedme Posted September 2, 2011 Share Posted September 2, 2011 When developing rounds, I load of 10 of each to test functionality and hone in on my velocity target. For final testing I bracket the velocity target and load 30 rounds of each - 20 for the chrono and 10 to test accuracy before I go into production with my final selection. Link to comment Share on other sites More sharing options...
StravIs09 Posted March 6, 2012 Share Posted March 6, 2012 sounds like a big waste of ammo to shoot 30 X multiple loads you are testing. not saying its a bad thing to get you load 100%. but i dont play it that close making my load right on the 165 pf major minimum. I load to 170+ if it doesnt make 170 avg on 5 shots then you got to go back and try some more powder. dont be afraid to shoot ammo at 172-175pf. Link to comment Share on other sites More sharing options...
Skydiver Posted March 6, 2012 Share Posted March 6, 2012 5 shots gives you a good idea of what the average is. Usually a test population of 20-30 gives you a very good idea of your standard deviation. Link to comment Share on other sites More sharing options...
bbbean Posted March 6, 2012 Share Posted March 6, 2012 sounds like a big waste of ammo to shoot 30 X multiple loads you are testing. not saying its a bad thing to get you load 100%. but i dont play it that close making my load right on the 165 pf major minimum. I load to 170+ if it doesnt make 170 avg on 5 shots then you got to go back and try some more powder. dont be afraid to shoot ammo at 172-175pf. It makes perfect sense if: 1) You want to be completely relaxed in the chrono tent, and 2) You understand the potential of a combination of outliers, production variability, and Murphy's law. BB Link to comment Share on other sites More sharing options...
motosapiens Posted March 6, 2012 Share Posted March 6, 2012 (edited) sounds like a big waste of ammo to shoot 30 X multiple loads you are testing. not saying its a bad thing to get you load 100%. but i dont play it that close making my load right on the 165 pf major minimum. I load to 170+ if it doesnt make 170 avg on 5 shots then you got to go back and try some more powder. dont be afraid to shoot ammo at 172-175pf. It makes perfect sense if: 1) You want to be completely relaxed in the chrono tent, and 2) You understand the potential of a combination of outliers, production variability, and Murphy's law. BB I suspect that being relaxed in the chrono tent has more to do with faith than with statistics and probability. I'd rather test 5-10 rounds each at 3-4 different chrono sessions than 30 all at once, but that's how my faith works. USPSA chrono procedures are pretty forgiving. ymmv. Edited March 6, 2012 by motosapiens Link to comment Share on other sites More sharing options...
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