Mossberg International 81 Bolt Action - Manual (Page 7)

When the bolt is removed from the rifle, the striker pin assembly may
become shifted into the released position. The bolt cannot be reinstalled
in the receiver if the striker is in the released position. To recock the
striker, hold the bolt handle, pull back on the striker and turn it clockwise
to lock it in the cocked position. See Fig. 4b.
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