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Powder temperature sensitivity
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<blockquote data-quote="BradS" data-source="post: 1103615" data-attributes="member: 91405"><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span><span style="font-size: 12px"><span style="font-family: 'Calibri'">I have results from the weekend testing that I did to determine temperature effects on cartridges. I have been experimenting with the same round for about 2 years and have worked up a load and controlled as many variables as possible. I have seen that the velocity is about 1% higher with cold Retumbo powder VS a warm Retumbo powder load. I have also seen that low primer weight hurts the velocity. I am surprised by the temperature correlation, this does not follow the other results that people have posted previously.</span></span></p><p> </p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">Summary Results (July 25 2015): </span></span></p><p> <span style="font-size: 12px"><span style="font-family: 'Calibri'">==========================</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">1. -20C VS 25C cartridge (as described below) is ~1% faster for the cold cartridge.</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">2. Low primer weight is nearing 1% slower than nominal or high primer weight. I have done this experiment 4 times now, there is a definite correction on CCI 250 and weight.</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">Here is the experiment:</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">Background:</span></span></p><p> <span style="font-size: 12px"><span style="font-family: 'Calibri'">==========</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">Cartridge: 7mm Rem Mag</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span><span style="font-family: 'Calibri'"><span style="font-size: 12px">Brass: Norma (I have weighed it all to within +-1.5grains.)</span></span></p><p><span style="font-family: 'Calibri'"><span style="font-size: 12px"></span><span style="font-size: 12px"> Bullet: 150.2grain Barnes T-TSX</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span><span style="font-size: 12px"><span style="font-family: 'Calibri'">Primer: CCI 250, (1 lot) Weighed to 5.18grains (0.02grain resolution on the scale).</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span><span style="font-size: 12px"><span style="font-family: 'Calibri'">Powder: Retumbo, 75.0 grains, (all one lot)</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span><span style="font-size: 12px"><span style="font-family: 'Calibri'">Brass: fired 6 times, at max brass length, never trimmed, but still in spec.</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span><span style="font-size: 12px"><span style="font-family: 'Calibri'">Neck Resized: 0.311"</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span><span style="font-size: 12px"><span style="font-family: 'Calibri'">Headspace: 0.008"</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span><span style="font-size: 12px"><span style="font-family: 'Calibri'">Finished Round: 3.10" setting - Redding dies (Measured to be 3.15-3.19") </span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span><span style="font-size: 12px"><span style="font-family: 'Calibri'">Concentricity: +- 0.002" (not corrected, just measured)</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span><span style="font-size: 12px"><span style="font-family: 'Calibri'">Load Environment: 72F, 50% humidity (estimate).</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span><span style="font-size: 12px"><span style="font-family: 'Calibri'">Equipment: RCBS digital powder measure, Redding competition dies.</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span><span style="font-size: 12px"><span style="font-family: 'Calibri'">Gun: Sauer 202</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">Final Ammunition:</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span><span style="font-size: 12px"><span style="font-family: 'Calibri'">===============</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">Label (1a) As above but 20x rounds with primers at 5.22grains.</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">Label (1b) As above but 20x rounds with primers at 5.14grains.</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">Label (1c) As above, nominal 40x rounds with primers at 5.18grains.</span></span></p><p> </p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">The Experiment:</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">=============</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">1. cold soaked 10 rounds of the (1c) above at -20C for 8 hours, put them in a cooler with thermal mass at -20C.</span></span></p><p> </p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">2. Using a Magnetospeed-V3 Chronograph, I shot 1 shot out of a clean gun, then waited 90s I shot the following sequence:</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'"> - 1 shot (1c, 5.18gn) @ -20C), wait 90s</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'"> - 1 shot (1c, 5.18gn) @ +25C), wait 90s</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'"> - 1 shot (1b, 5.14gn) @ +25C), wait 90s</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'"> - 1 shot (1a, 5.22gn) @ +25C), wait 90s</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'"> - Repeat the above 4 shot sequence 7 more times, for a total of 32 shots.</span></span></p><p> </p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">Notes:</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">A) The cold ammunition was shot with 10s of being removed from the cooler.</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">B) The gun got hot, but not too hot to touch, my shotgun gets a lot hotter when I do 25 shots at trap shooting).</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">C) I have changed my Chronograph to the Magnetospeed-V3 last year to eliminate the error caused by the equipment. (the Magnetospeed clamps onto the barrel). I had been using an RCBS Ammo-master, however the error caused by the placement of the sensors each time was +- 30fps. It made the measurements impossible to correlate:</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">Results:</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">=======</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">-First shot 1-shot average 3048fps.</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">-(1c @25C) 8-shot average 3053fps, Spread 28fps.</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">-(1c @-20C) 8-shot average 3080fps, Spread 60fps.</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">-(1b @25C) 8-shot average 3027fps, Spread 40fps.</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">-(1a @25C) 8-shot average 3049fps, Spread 24fps.</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">Average for all 33-shots, 3061fps +- 50fps (3011fps to 3111fps)</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px"> </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">Discussion:</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">=========</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">I went back though my notebook and found an identical load that I shot on October 30 2014 with the same lots of powder and primer. The 11-shot average was 3070fps at -2C. I am going to keep the ammunition until the outside temperature drops to 0C and repeat with -20C, 0c and +25C ammunition from load labeled (1c).</span></span></p><p> </p><p><span style="font-size: 12px"><span style="font-family: 'Calibri'">Has anyone ever seen these kinds of results? Could it be something to do with the </span></span><span style="font-size: 12px"><span style="font-family: 'Calibri'">bullet friction on the barrel etc...? (these are full copper bullets) </span></span></p></blockquote><p></p>
[QUOTE="BradS, post: 1103615, member: 91405"] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT][SIZE=3][FONT=Calibri]I have results from the weekend testing that I did to determine temperature effects on cartridges. I have been experimenting with the same round for about 2 years and have worked up a load and controlled as many variables as possible. I have seen that the velocity is about 1% higher with cold Retumbo powder VS a warm Retumbo powder load. I have also seen that low primer weight hurts the velocity. I am surprised by the temperature correlation, this does not follow the other results that people have posted previously.[/FONT][/SIZE] [SIZE=3][FONT=Calibri] [/FONT][/SIZE] [SIZE=3][FONT=Calibri]Summary Results (July 25 2015): [/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT][SIZE=3][FONT=Calibri]==========================[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT] [SIZE=3][FONT=Calibri]1. -20C VS 25C cartridge (as described below) is ~1% faster for the cold cartridge.[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT] [SIZE=3][FONT=Calibri]2. Low primer weight is nearing 1% slower than nominal or high primer weight. I have done this experiment 4 times now, there is a definite correction on CCI 250 and weight.[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT] [SIZE=3][FONT=Calibri]Here is the experiment:[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT] [SIZE=3][FONT=Calibri]Background:[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT][SIZE=3][FONT=Calibri]==========[/FONT][/SIZE] [SIZE=3][FONT=Calibri]Cartridge: 7mm Rem Mag[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT][FONT=Calibri][SIZE=3]Brass: Norma (I have weighed it all to within +-1.5grains.) [/SIZE][SIZE=3] Bullet: 150.2grain Barnes T-TSX[/SIZE][/FONT] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT][SIZE=3][FONT=Calibri]Primer: CCI 250, (1 lot) Weighed to 5.18grains (0.02grain resolution on the scale).[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT][SIZE=3][FONT=Calibri]Powder: Retumbo, 75.0 grains, (all one lot)[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT][SIZE=3][FONT=Calibri]Brass: fired 6 times, at max brass length, never trimmed, but still in spec.[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT][SIZE=3][FONT=Calibri]Neck Resized: 0.311"[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT][SIZE=3][FONT=Calibri]Headspace: 0.008"[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT][SIZE=3][FONT=Calibri]Finished Round: 3.10" setting - Redding dies (Measured to be 3.15-3.19") [/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT][SIZE=3][FONT=Calibri]Concentricity: +- 0.002" (not corrected, just measured)[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT][SIZE=3][FONT=Calibri]Load Environment: 72F, 50% humidity (estimate).[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT][SIZE=3][FONT=Calibri]Equipment: RCBS digital powder measure, Redding competition dies.[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT][SIZE=3][FONT=Calibri]Gun: Sauer 202[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT] [SIZE=3][FONT=Calibri]Final Ammunition:[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT][SIZE=3][FONT=Calibri]===============[/FONT][/SIZE] [SIZE=3][FONT=Calibri]Label (1a) As above but 20x rounds with primers at 5.22grains.[/FONT][/SIZE] [SIZE=3][FONT=Calibri]Label (1b) As above but 20x rounds with primers at 5.14grains.[/FONT][/SIZE] [SIZE=3][FONT=Calibri]Label (1c) As above, nominal 40x rounds with primers at 5.18grains.[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT] [SIZE=3][FONT=Calibri]The Experiment:[/FONT][/SIZE] [SIZE=3][FONT=Calibri]=============[/FONT][/SIZE] [SIZE=3][FONT=Calibri]1. cold soaked 10 rounds of the (1c) above at -20C for 8 hours, put them in a cooler with thermal mass at -20C.[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT] [SIZE=3][FONT=Calibri]2. Using a Magnetospeed-V3 Chronograph, I shot 1 shot out of a clean gun, then waited 90s I shot the following sequence:[/FONT][/SIZE] [SIZE=3][FONT=Calibri] - 1 shot (1c, 5.18gn) @ -20C), wait 90s[/FONT][/SIZE] [SIZE=3][FONT=Calibri] - 1 shot (1c, 5.18gn) @ +25C), wait 90s[/FONT][/SIZE] [SIZE=3][FONT=Calibri] - 1 shot (1b, 5.14gn) @ +25C), wait 90s[/FONT][/SIZE] [SIZE=3][FONT=Calibri] - 1 shot (1a, 5.22gn) @ +25C), wait 90s[/FONT][/SIZE] [SIZE=3][FONT=Calibri] - Repeat the above 4 shot sequence 7 more times, for a total of 32 shots.[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT] [SIZE=3][FONT=Calibri]Notes:[/FONT][/SIZE] [SIZE=3][FONT=Calibri]A) The cold ammunition was shot with 10s of being removed from the cooler.[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT] [SIZE=3][FONT=Calibri]B) The gun got hot, but not too hot to touch, my shotgun gets a lot hotter when I do 25 shots at trap shooting).[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT] [SIZE=3][FONT=Calibri]C) I have changed my Chronograph to the Magnetospeed-V3 last year to eliminate the error caused by the equipment. (the Magnetospeed clamps onto the barrel). I had been using an RCBS Ammo-master, however the error caused by the placement of the sensors each time was +- 30fps. It made the measurements impossible to correlate:[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT] [SIZE=3][FONT=Calibri]Results:[/FONT][/SIZE] [SIZE=3][FONT=Calibri]=======[/FONT][/SIZE] [SIZE=3][FONT=Calibri]-First shot 1-shot average 3048fps.[/FONT][/SIZE] [SIZE=3][FONT=Calibri]-(1c @25C) 8-shot average 3053fps, Spread 28fps.[/FONT][/SIZE] [SIZE=3][FONT=Calibri]-(1c @-20C) 8-shot average 3080fps, Spread 60fps.[/FONT][/SIZE] [SIZE=3][FONT=Calibri]-(1b @25C) 8-shot average 3027fps, Spread 40fps.[/FONT][/SIZE] [SIZE=3][FONT=Calibri]-(1a @25C) 8-shot average 3049fps, Spread 24fps.[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT] [SIZE=3][FONT=Calibri]Average for all 33-shots, 3061fps +- 50fps (3011fps to 3111fps)[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT] [SIZE=3][FONT=Calibri]Discussion:[/FONT][/SIZE] [SIZE=3][FONT=Calibri]=========[/FONT][/SIZE] [SIZE=3][FONT=Calibri]I went back though my notebook and found an identical load that I shot on October 30 2014 with the same lots of powder and primer. The 11-shot average was 3070fps at -2C. I am going to keep the ammunition until the outside temperature drops to 0C and repeat with -20C, 0c and +25C ammunition from load labeled (1c).[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT] [SIZE=3][FONT=Calibri]Has anyone ever seen these kinds of results? Could it be something to do with the [/FONT][/SIZE][SIZE=3][FONT=Calibri]bullet friction on the barrel etc...? (these are full copper bullets) [/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT] [/QUOTE]
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