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Posted: 4/27/2009 7:47:31 PM EDT
| I'm new to reloading and I have a neighbor that has been doing it for years. He told me that him and a buddy had loaded for a IDPA match that was in a different location At the match they were checking the power factor and they were +10 from what they had loaded which was fine but they didn't want to be that high. So my question is does weather/climate affect the power factor? If so I will be heading down to Texas next month for a IDPA match and was wondering if there is anyone from there that reloads 9 mm (XDm 9) that has a good formula for there area.? If this makes no sense forgive me as I have stated I' am new to all this and I' am testing loads that will work for my XDm 9. Right now i' am loading 124gr with 4.2 TG and this seem's to fine. Thanks for any info. |
| Powders can be temperature sensitive. I recall a story in American Handgunner where the tempterature was unseasonably cold during the testing of the ammo during some major match and a lot of competitor's ammo was chronographing much slower than the competitors had anticipated and they were forced to shoot in the lower power class. They said a lot of guys were putting their ammo in front of the heater vents in their cars in order to try to get better readings. I guess you would have to get some weather info for the area the match is in and try to simulate that while working your charges up. |
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Quoted:
Thanks for clarifying. It's about 45-50 degress here in WA and I'm sure it should be 70 to 80 degress in TX, so I guess my next question would be is when it is hot the power factor will rise and when it is cold the power factor will drop? I would think that is the case. |
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Quoted:
Quoted:
Thanks for clarifying. It's about 45-50 degress here in WA and I'm sure it should be 70 to 80 degress in TX, so I guess my next question would be is when it is hot the power factor will rise and when it is cold the power factor will drop? I would think that is the case. Yes, it should. If you load to a velocity that's just AT the power factor, you'll be at or above in the hotter temp.............won't lose anything, at least. Yes, I do load 9mm, but no, I don't have a chrono  , so not sure if I could steer you in the direction that's gonna give you enough velocity to make your power factor for sure.
I myself have been using 4.4 grns of Titegroup or 4.8 grns of .W231 under a 115 grn JHP, OAL at 1.085. They're not all that hot though. |
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Quoted:
Thanks for clarifying. It's about 45-50 degress here in WA and I'm sure it should be 70 to 80 degress in TX, so I guess my next question would be is when it is hot the power factor will rise and when it is cold the power factor will drop? This is USUALLY the case. There are some exceptions with some powders. Back in the late 80s/early 90s a friend talked me into switching from my (working just fine) load with Win.231 to Win.452. He said it was cleaner/used less/blaa blaa blaa I worked up a load in cooler weather and it worked great. Summer time came around and I started to experience stove pipes. I tried extractors, springs, different OALs, couldn't get it worked out, but then it turned cooler, it stopped doing it, so I moved on, not even considering cooler weather. The next summer, the problem came back. Once again, I tried all the tricks. I didn't even consider powder because I use a Lee disk measure with the hole marked so as to get the same charge each time. While getting agrivated by it at a match, a friend asked what powder I used. He said to chrono it in the heat, as he had the same problem, and found a major drop in velocity in the summer 95 Deg. and above heat. I chronoed it that week, and the velocity was a bit over 100 fps slower than my original records. I went back to 231, and have used it since then. What you are using should work just fine. Good luck. |
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