Below is an excerpt straight from the armorer's manual. The question about the "sight base" is simple...the further apart, the better.
Sight Adjustment
· The rear sight drum has a “V” notch marked “1” and three diopters marked “2”, “3” and “4”
· The rifle should be sighted-in at 100 yards using the “V” notch. The top of the front sight blade should be even with the top of the rear sight “V”
and centered.
· If the shooter’s target is at 200 yards, the drum should be rotated so the “2” diopter is now facing the shooter’s eye.
· The diopter has been moved up to compensate for the extra 100 yards.
· The “3” diopter should be used for 300 yards and the “4” for 400 yards
· In effect, once the rifle is sighted-in at 100 yards with the “v” notch, the rifle is also sighted-in @ 200, 300 and 400 yards
· Sighting through any of the diopters the shooter should obtain an equal halo of light around the front sight mount positioning the front sight blade in the center.
The sights on the HK rifles can be adjusted for elevation and windage.
Sight adjustment tool
There are two parts to the sight adjustment tool.
· A short shank Phillips head screwdriver
· The spring loaded tab assembly
The tabs are spring-loaded and will always move outward at the tips. The insertion of the screwdriver from the bottom of the tab assembly will bring the tab tips inward towards each other. It is this manipulation of the tabs that will capture the detents holding the rear sight drum in place.
Sight adjustments
Remember this formula:
LL=C (Lower or Left = Clockwise rotation)
The sight adjustment is a rear sight adjustment, so the movement of the sight will be in the same direction the shooter wants the impact of the round to move. If the hit is to the right of the intended location, then the sights and the impact must be moved left.
Elevation: one-complete rotation (360o) of the rear sight drum will shift the impact of the round approximately 6 inches @ 100yards.
Windage: one-complete rotation (360o) of the windage screw will shift the impact of the round 6 inches @ 100 yards
Elevation Adjustment
1. Insert the screwdriver shaft into the bottom of the adjustment tool. This will bring the tabs towards the center.
2. Place the tabs inside the rear sight drum and on top of the detents
3. Hold the tool in place and remove the screwdriver. This will release the tabs to the outside of the detents.
4. Re-insert the screwdriver holding the tool very steady. This will again bring the tabs and this time the detents to the center unlocking the rear sight drum. Turning the screwdriver or tool does nothing; they must remain still while the drum is turned. Make the sight adjustment for elevation and remove the sight tool.
Windage Adjustment
Unscrew the large Phillips head screw of the top rear of the sight approximately one-eighth of a turn, just enough to loosen it.
Insert the Phillips head screwdriver into the wind age screw on the right side of the rear sight base. Turn this screw to make the proper wind age adjustment. Retighten the top Phillips head screw.
