CALCULATING DUD AND MISFIRE PERCENTAGE RATES
Dud and misfire percentage rates are calculated by dividing the number of malfunctions by the total number of
rounds expended. For example, a using unit expends 30 fragmentation grenades. Two of these are duds. Table
B-1 in AR 75-1 (see the extract on page A-2) shows that two grenade duds make a reportable number. The defect
rate is calculated as follows:
2 (duds) 30 (expended) = .07 x 100 = 7 percent
Table B-1 shows that the reportable defect rate for grenades is five percent. The seven percent rate exceeds the
reportable rate.
Normally, the total quantity used in the calculation will be the quantity fired by the using unit in a particular day.
However, if satisfactory records are kept, a cumulative total for a certain lot fired by other units on other days may
be compiled. Records for time periods of up to 30 days may be used. For example, a using unit fires 62 mortar
rounds and has four duds. This makes a six percent dud rate, which is reportable according to Table B-1.
However, other units over the past 30 days have fired 238 rounds of the same lot and have had only six duds.
Using the total duds and the total rounds, the cumulative defect rate is calculated as follows:
4 + 6 = 10 total duds
62 + 238 = 300 total rounds expended
10 300 = .0333 x 100 = 3.33 percent
Table B-1 shows that the reportable rate is five percent. The cumulative defect rate in this case is 3.33 percent.
Therefore, this dud rate is not reportable.
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