varminter22 Posted January 8, 2014 Share Posted January 8, 2014 What steps do you take to ensure you make power factor when traveling out of your area? Is there a 'general rule' to follow? For example, I'm currently shooting a M627 with .38 Short Colt, 142 Montana Gold FMJ, 3.3 gr Tite Group, AOL ~ 1. 082" and making 127 PF at approximately 4000' elevation. As I understand it, I'll probably lose some velocity in Barry IL due to its lower elevation (730') and perhaps humidity too. Been planning to increase the charge a bit anyway but now I probably really should if I'm to travel to the Revolver Nationals. Same question would apply if traveling from here to the IRC which is virtually at sea level. By the way, also have WST (but wasn't happy with the one test I did in the Short Colt), some N320 (haven't tried yet), and Clays (which I don't think is suitable with 142 and 147 gr bullets.) Link to comment Share on other sites More sharing options...
Aircooled6racer Posted January 8, 2014 Share Posted January 8, 2014 Hello: Use the N320 and increase the power factor to 131-134 at 4000'. You will be safe all over the country with that. Thanks, Eric Link to comment Share on other sites More sharing options...
varminter22 Posted January 9, 2014 Author Share Posted January 9, 2014 Thanks. I will try the N320. And perhaps retest with 3.4 and 3.5 gr Tite Group. Link to comment Share on other sites More sharing options...
Hi-Power Jack Posted January 9, 2014 Share Posted January 9, 2014 Going to The Nationals with PF 127 is asking for trouble. My guess is that you would have a difficult time feeling the difference between PF 127 and PF 135, it wouldn't slow you down one bit, but you'd be a LOT safer at the chrono. Link to comment Share on other sites More sharing options...
varminter22 Posted January 9, 2014 Author Share Posted January 9, 2014 Roger that! I was planning to increase the PF. Just wondered if there is a general rule as to how much difference to expect going from 4000' to lower elevation. Link to comment Share on other sites More sharing options...
Grump Posted January 10, 2014 Share Posted January 10, 2014 My ballistics programs really don't detect much of a difference for air density from the muzzle to the center of the Chrono screens. TEMPERATURE effects are more commonly the bugaboo for velocity, not altitude or humidity or latitude or Coriolis effect. Handgun bullets and speeds? Atmospherics can change things a fraction of an inch on POI, and measurable numbers of lower velocity start showing up beyond 25 yards, they might result in a tiny zero shift at 50, and still probably won't throw you out of the A zone at 100. I still see the long range rifle guys fret about *chrono* readings at different altitudes, but you'd be hard pressed to get more than a 10 fps difference in speed the first 8 feet downrange. Link to comment Share on other sites More sharing options...
varminter22 Posted January 10, 2014 Author Share Posted January 10, 2014 Thanks. I will try to increase PF to the low 130s. Darned sure wouldn't want to go sub-minor! Link to comment Share on other sites More sharing options...
RePete Posted January 10, 2014 Share Posted January 10, 2014 Thanks. I will try to increase PF to the low 130s. Darned sure wouldn't want to go sub-minor! As a chronographer at some major matches, I recommend about 134PF. I run 137 and 149 (40S&W minor). Link to comment Share on other sites More sharing options...
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