Problem: your periscope sight is linked to the gun!

RANGE UP (default: MOUSESCROLLWHEEL)
IRONSIGHTS TOGGLE (default: RMB)

You now have an independent periscope!

INTERACTION (default: CTRL) to link or un-link gun or PRIMARY FIRE (default: LMB) to link only.

Also see:
http://insurgencymod.blogspot.com/2011/12/ro-cunning-and-tactics.html

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