M2/M3 BFV: FIRE CONTROL SYSTEM - OD1608 - LESSON 1/TASK 1
and the commander to see the same thing at the same time. High (12X)
or low (4X) magnification can be selected for both day and night
Select switches on the ISU allow controlled day and night
viewing for aiming with the use of reticle displays.
displays tell which weapon, range, and ammunition have been selected.
The boresight controls (figure 2 on the previous page) on the ISU and
boresighting kits help to boresight the guns and the TOW launcher.
(2) Backup Sight. The backup sight is a mechanical sight used
in the event of an ISU failure. It allows aimed daylight firing of
the 25mm gun in the AP or HE mode. It provides 5X magnification and
a line of sight elevation of -10 to +60. The eyepiece of the backup
sight can be positioned for use by the gunner or commander.
Boresighting the 25mm Gun
Anyone who uses a weapon knows that aiming is an important part of
firing. If the gunner is looking at a target in one place, but the
gun is pointed elsewhere, the ability of the gunner to achieve
accurate firing on target is severely impaired. Boresighting is the
procedure that makes sure that the weapons and sighting devices are
all operating on the same lines of sight, so that, when the
ammunition is fired, it will have the best possible chance of hitting
the target that is being sighted.
Since this is the case, it is
normal to boresight the major components of the weapons system in
sequence during the same maintenance period. First, the 25mm gun is
boresighted, and then the other components are matched to its
established line of sight.
This subcourse assumes that the mechanic is
familiar with the general operation of the
weapons and the turret.
such as manually traversing the turret or
engaging the turret travel lock will not be
discussed in detail here.
Instead, the first
time a general operating procedure is mentioned
in the subcourse text, reference will be made to
the appropriate technical manual page.