[old roper]

Here is where I got number.

SECTION II – PROCEDURES
CENTERFIRE RIFLE
REFERENCE AMMUNITION:
PERIODIC ASSESSMENT
SAAMI VOLUNTARY PERFORMANCE STANDARDS

varies from the Raw Average by more than plus or minus 50 fps in velocity OR
plus or minus 3,500 CUP/psi in pressure, the pressure or velocity data from that
(those) station(s) should be discarded. The mean pressure and velocity data
should be recalculated omitting the discarded data. The new mean is the
“Corrected Average”. If the mean pressure value of a station is outside of the
limits as defined above, but the velocity is in, the pressure data should be dropped
and the velocity data retained. The converse is true as well. Using the Corrected
Averages, the Inclusion Limits are determined as follows:
VELOCITY: MEAN = Same as Corrected Average
HIGH = MEAN + 50 fps
LOW = MEAN – 50 fps
PRESSURE: MEAN = Same as Corrected Average
HIGH = MEAN + 3,500 CUP/psi
LOW = MEAN – 3,500 CUP/ps