USPSA Handgun Competition Rules January 2008

33. Conventions to be used for all measurements:
a. if more than one chronograph is in use, the highest velocity recorded
by any of the chronographs shall be used for each respective shot.
b. if more than one scale is in use concurrently, the highest weight measured
by the scales shall be used for each respective bullet weighed
34. From the eight sample rounds drawn by Match Officials, one bullet is
weighed to determine the actual bullet weight and three bullets are fired
over the chronograph. Digits displayed on the official match bullet scales
and chronograph will be used at face value, irrespective of the number of
decimal places indicated on the measuring device used at the match.
35. Power factor is calculated using the bullet weight and the average velocity
of the three rounds fired, according to the following formula:
Power Factor = bullet weight (grains) x
average velocity (feet per second) /
1000
The final result will ignore all decimal
places (e.g. for USPSA purposes, a
result of 124.9999 is not 125).
36. If the resultant power factor fails to meet the declared power factor floor,
another three rounds will be fired over the chronograph. The power factor
will be recalculated using the bullet weight and the average velocity of the
three highest velocity rounds from the six rounds fired.
37. If the power factor is still insufficient, the competitor may elect to have:
a. the final bullet pulled and weighed and, if heavier than the first bullet,
the power factor calculation in Paragraph 35 will be recalculated using
the heavier bullet weight, or
b. the final round fired over the chronograph and the power factor recalculated
using the first bullet weight, and the average velocity of the
three highest velocity rounds from the seven rounds fired.
38. If the resultant power factor fails to meet the Major power factor floor of the
relevant Division, the competitor’s entire match scores will be recalculated
as Minor, if achieved.
39. If the resultant power factor fails to meet the minimum power factor floor
for the relevant Division, the competitor may continue shooting the match,
but not for score or match recognition.
40. Due to the different methods used by certain chronograph brands to calculate
Power Factor, any power factor results produced by the Chrono Station
chronograph are considered interim results and subject to confirmation.
a. The only official power factor results are produced and/or confirmed
by using the formula specified in Item 35 or via the EzWinScore scoring
program.
68 • USPSA Handgun Rules, January 2008 Edition