Boresighting the 25mm Gun

The M2/m3 Bradley Fighting Vehicle: Fire Control System
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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.

NOTE

This subcourse assumes that the mechanic is

familiar with the general operation of the

weapons and the turret.

Therefore, procedures

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.