Thanks Zupermann and AJCrowley, for the info
I got the Dual Optic from a reputable HK authorized Canadian dealer and it did not come with any mounting bolts or instructions, question for you, do you happen to know what the following item is (circled in red on both pics)?
Found the installation and adjustment info online, posted below to share with all.
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Sight Installation
HECKLER & KOCH, INC
21480 PACIFIC BOULEVARD
STERLING, VIRGINIA 20166-8903 USA
WARNING
Clear the Rifle!
To install the Dual Sighting System on the G36 or SL8-1, first "clear" the rifle by placing the safety/selector lever in the safe position, removing the magazine from the rifle, locking the bolt rearward and inspecting the chamber for the presence of a cartridge or empty case.
1. Once the rifle is "clear" use a Phillips head screwdriver or the HK Multi-tool supplied with each SL8-1, to loosen and remove the three mounting screws that hold the standard sight in place.
2. Pull the standard sight rearward off of the receiver of the rifle.
3. Slide the Dual Sighting System over the rear end of the receiver dovetail and push it forward into place on the rifle. Insure that the front extension of the carrying handle fits over the front mounting pedestal located on the rifle forward of the cocking lever.
4. Once fully seated, reinstall the three locking screws to secure the sight to the rifle.
NOTE
The longest of the three screws received with the Dual Sighting System (1 1/2 inches in length) goes in the front end of the carrying handle. The two shorter screws (1 3/16 inches in length) are installed in the holes provided in the rear of the carrying handle under the optical sight.
When inserting the screw place one unthreaded washer under the head of the each screw. Insert the screws in the rifle from left to right. Install the threaded nuts on the end of the screws visible from the right side of the carrying handle. Hand tighten the screws using a Phillips head screwdriver or the HK SL8-1 Multi-tool. If using a torque screwdriver to tighten the screws set the torque setting to 250 NCM (22.5 inch pounds).
5. After mounting zero or reconfirm the zero of the sight(s) by following the directions provided in the operators manual for the rifle. Unless the proper torque setting is used when the sight is remounted there may be minor zero changes after remounting.
Use of the Dual Sighting System
Optical Sight
The use and adjustment of the Optical Sight, to include the features and function of the unique reticule pattern provided within the sight, is explained in the operator’s manual for the rifle.
Electronic Red Dot Reflex Sight
The red dot within the upper sight of the dual sighting system is powered by ambient light through a solar collector or by means of a battery contained within the sight. During normal daylight conditions with the solar collector shade on top of the dual sight open (slide forward) the solar collector will illuminate the red dot as long as sufficient ambient light is available to do so. The dot will glow brighter in stronger outdoor sunlight than it will indoors or under artificial light. For periods when very little ambient light is available or when the shooters prefers a brighter red dot, the battery back up can be switched on.
Turning the Red Dot Sight On and Off
The on/off switch for the red dot sight is located on the right rear end of the dual sighting system. Rotating this switch COUNTERCLOCKWISE will turn the sight ON (when the white line aligns with the white dot), CLOCKWISE will shut the sight OFF (when the white "0" aligns with the white dot - remember "0" means "off').
The red dot cannot be adjusted for brightness or size nor are there intermediate positions within the rotary on/off switch. The relatively large red dot is designed primarily for quick instinctual aiming and not finite precision. For precision engagements of small or distant targets the fine reticule within the optical sight of the Dual Sighting System should be used.
If desired the shade of the solar collector can be closed to hide the glow of the battery- illuminated collector during periods of darkness.
Changing the Red Dot Sight Battery
The Red Dot Sight uses only a single 3.6-volt size AA Lithium Battery. One manufacturers model number for this battery is SL- 760. It is available at many local stores, from Radio Shack or from HK directly under ID# 986444.
NOTE
Do not attempt to use other types of batteries in the red dot sight other than that specified above or poor performance or damage to the sight may occur and is not covered under warranty.
To remove the battery, locate the battery compartment positioned to the left of the red dot sight opposite the on/off switch. Use a coin inserted within the slotted cover to rotate the battery compartment 1/8th turn counterclockwise. The battery compartment can then be pulled out only far enough to remove and install the battery. DO NOT attempt to completely remove the battery compartment. The correct orientation for the battery is noted within the battery compartment. To close the battery compartment push in on and rotate the slotted cover 1/8th clockwise until secure.
Dual Sighting System Maintenance
If the red dot fails to illuminate when the battery on/off switch is turned on or the red dot flickers or is hard to see, try exchanging the battery with a fresh one. If this fails to improve matters clean the battery contacts within the battery compartment using a cotton swab and rubbing alcohol. If problems persist, contact your unit armory, your HK dealer or Heckler & Koch.
DO NOT attempt to disassemble the Dual Sighting System for any reason. The solar collector and red dot and optical sight lens should be cleaned with lens cleaning tissues only to avoid scratching the lens.
DO NOT immerse the Dual Sighting System in cleaning solvent as damage to the sights lens and rubber and electronic components may occur and is not covered under warranty.
Zeroing
Due to the unique design of the Dual Sighting System both sights can be independently zeroed for the same or different ranges. For instance a hunter might prefer a long range zero (200 meters) for the optical sight for longer shots and a 50 meter zero for closer shots on moving targets or when the lighting conditions worsen.
The standard factory zero for rifles equipped with the Dual Sighting System is a 200 meter (219 yard) zero. Once established the 200 meter zero will insure that the aiming points provided within the Optical Sight reticle will correspond to the targets fired at longer distances when using 55 or 62 grain ammunition (results may vary with different types and brands of ammunition). The Red Dot Sight can also be adjusted using the same 200-meter zeroing procedure described below.
Zeroing Procedure
The intersection of the Optical Sight crosshairs within the thick black aiming circle, or the red dot of the reflex sight, should be used for zeroing.
1. With a target placed 25 meters (27.5 yards) from the firing position, adjust the impact of the rounds on target until the center of a good 3-shot group passes through the target 1 31. inches (45 mm) low of the point of aim. This will provide a 200 meter zero without the need to fire on or have access to a 200-meter range.
2. Consult the applicable operators manual for the rifle being fired for the method, direction of movement and degree of adjustment for the Optical Sight, which are also the same for both sights within the Dual Sighting System.
3. Use the 2.5 mm Allen wrench contained within the HK SL8-1 Multi-tool to make windage and elevation adjustments.
