Chrono Questions

I recently received a technical question from a friend and viewer (Rock):

Will a change from our close-to-sea-level altitude here in the valley, to Bend/Central Oregon, approx. 3300’, have an effect on 9mm ammo that is normally about 127 power factor? 1110 fps X 115 Gr?

This is a reasonable question, and one which has plagued competitive shooters since IPSC was invented  (shortly before Christ was promoted to Corporal).  After serious reflection, I decided to address this important technical question.

Taking into consideration all of the salient factors, this was my reply:

Altitude difference will influence measured power factor inevitably, and usually to the detriment of the shooter.

Other factors which may lower a competitors power factor include, but are not restricted to:

• Humidity
• Ambient Temperature
• Time of day
• Exposing your ammunition to the heat of the sun
• a dirty barrel (always clean and oil your firearm before going to the Chronograph Stage!)
• Different brass, powder, primer or bullet .. not just weight (bullet and powder charge), but lot and brand
• Length of time since your ammunition has been loaded
• The number of times you have reloaded your ammunition
• Your religion; are you "Good With The Lord"?
• How long since you have bathed?   [Whew!]
• The cost and importance of the match
• Travel time and inconvenience of timing of the match
• How long since you have chronographed your load
• The physical characteristics of your firearm
• Your personality: "jerks" never chronograph as Minor
• If you  squad with your spouse or child, one of you will be Minor Power (or under!) with the same ammunition
• Your financial situation:  have you slipped a ten-spot to the Chrono Crew?

Hope this helps.


Jerry

Don't thank me ... it's my job to be helpful.