Setup

Red Dot Sight Adjustment

The only thing to keep in mind is that when you make adjustment to the sight per the sight's markings you are actually moving the camera's focus point. I.e. if you turn the adjustment screw towards "up" the camera's focus point moves up, not the sight's reticle. The easiest way to zero the sight is to place the monorail onto a tripod and turn on live view. Next place the center focus point on a point at an "average shooting distance" and lock down the tripod head. Now just move the sight reticle until it' s on the same point as the center focal point is displaying in liveview.

CameraStock/ScopeStock Setup

The Sharpshooter Camera Mount is designed to be custom fit for user comfort and maximum stability.
To set up your system: First, mount the Mono Rail to the lens foot. If you are using a straight Mono Rail it should generally be mounted so that the back edge of the rail is just in front of the camera body. This allows the Camera body to be removed more readily.

You may be using a stepped Mono Rail which mounts to both the  lens foot and camera body, or  have the straight Mono Rail adjusted further back under the camera body for fit. In those instances the tripod collar on the lens should be loosened to facilitate body removal by rotating the lens.

(Note, strap mount can be mounted on top or below the Mono Rail in any available position.)

Next, fully loosen the   set screw (1/8"/ 3mm allen) and "slightly" loosen the mounting screw (5/32"/4mm allen). You want the clamp to be able to change position with some force, but to hold that position so you can lock it in when done.  

 (Note, the clamp can be reversed so that the knobs are on the opposite side. Simply move the set screw to the opposite end.)

The further offset the plate is from center line the more parallel to your body the camera will be when in shooting position. The more in-line the plate is the more in front of your body the camera will be. Having the camera too far in front of you makes it difficult to place the fore grip where it is supporting the weight well while anchoring the elbow into the ribs. (The image shows adjustment for a right handed person.)

Next attach the stock to MonoRail.

Now experiment with fit. The stock can be adjusted in length and mounting position along the Mano Rail. If you need to move the camera further away, even with the stock fully extended and at the back end of the rail, then you will need to move the lens further forward on the MonoRail.
The goal is to have both elbows tucked into the body with the weight resting primarily on the forward arm and the weight being transferred to the body. Everything should be comfortable and allow you to view thru the camera viewfinder or red dot sight mounted in the flash bracket.

Once you find what fits you best tighten all screws, but do not overtighten the set screw. Eventually, once you are certain the adjustments are ideal for you, you may want to use a small drill bit to create a hole for the set screw to go into. This is not necessary but will ensure the adjustment cannot shift.

If the camera is sitting too high; there are a couple of options. The first is to replace the lens foot with a shorter one.  Nikon's big lenses like the 400mm f/2.8 have this issue. If your lens came with the additional short foot you can use that without an issue. Most who did not get the short foot with their lens will have replaced it with an aftermarket version, and you might want to as well. Some use the system with  lenses that have a non-replaceable tall foot without issue. The other option is to get a reverse offset Mono Rail.

The rifle stock is water resistant with all electrical connections silicon sealed. However, the trigger switch itself is not waterproof.

On the bottom of the pistol grip there is a latched plate. This area can be used to store anything that is not terribly sharp (there are electrical connections inside there under a layer of silicoln sealant).

Release cables are shipped inside the pistol grip.

The butt plate can be removed to reduce weight/size. There is also a tubular area  under the plate that could be used to store something like AA batteries for a flash.