This is the distance from the sniper’s firing eye to the
rear sight or the rear of the scope tube. When using iron sights, the sniper
ensures the distance remains consistent from shot to shot to preclude
changing what he views through the rear sight. However, relief will vary
from firing position to firing position and from sniper to sniper, according
to the sniper’s neck length, his angle of head approach to the stock, the
depth of his shoulder pocket, and his firing position. This distance
(Figure 3-16) is more rigidly controlled with telescopic sights than with
iron sights. The sniper must take care to prevent eye injury caused by the
scope tube striking his brow during recoil. Regardless of the sighting
system he uses, he must place his head as upright as possible with his firing
eye located directly behind the rear portion of the sighting system.
This head placement also allows the muscles surrounding his eye to relax.
Incorrect head placement causes the sniper to look out of the top or
corner of his eye, resulting in muscular strain. Such strain leads to blurred
vision and can also cause eye strain. The sniper can avoid eye strain by
not staring through the telescopic or iron sights for extended periods.
The best aid to consistent eye relief is maintaining the same stock weld
from shot to shot.