vertical (EV) divided by two 2
shall be measured and recorded for
e a c h 10-shot target. M e a s u r i n g of targets shall be to the nearest tenth
o f an inch using the center of the bullet holes as reference points.
( b ) The average figure of merit for the group of 100 rifles
s h a l l be obtained by adding the figure of merit obtained for each of the
i n d i v i d u a l targets and then dividing by 100.
T h e formula is:
( c ) The standard deviation for the group of 100 rifles shall
b e calculated using the following formula (or equivalent):
D e f i n i t i o n of symbols used above:
number of targets
f i g u r e of merit of individual target
s t a n d a r d deviation of figure of merit
a v e r a g e figure of merit
4 . 5 . 7 . 1 . 4 If the average FM and the standard deviation are withtin
t h e requirement (see 220.127.116.11.1) the group of 100 rifles shall be con.
s i d e r e d as "process qualification rifles:" and shall be used to determine
t h e accuracy limits for individual rifle acceptance when using unselected
l o t s of ammunition (see 18.104.22.168). If the average FM and the standard
d e v i a t i o n are not within the requirements (see 22.214.171.124.1), the contractor
s h a l l determine the cause of failure and shall take necessary corrective
a c t i o n . A f t e r corrective action has been taken, all of the rifles shall
b e refired using the procedure specified above, At the discretion of
t h e Government representative refiring may be limited to only those
r i f l e s which caused the failure of the group and the data thus obtained
s u b s t i t u t e d for the original data for those rifles.
4 . 5 . 7 . 2 I n d i v i d u a l r i f l e a c c e p t a n c e . When using selected lots of
a m m u n i t i o n (see 126.96.36.199) i n d i v i d u a l r i f l e s s h a l l b e f i r e d 1 0 - s h o t
t a r g e t s for accuracy using the procedure specified in 188.8.131.52.2, and
t h e targets measured as specified in 184.108.40.206.3 (see 220.127.116.11.2). When
u s i n g unselected lots of ammunition (see 18.104.22.168), individual rifles