-The pistol grip for the shooting hand must not rest on your sling or on your other arm.
-No perforation of the barrel or extension tubes is allowed.
-There must be nothing special inside the barrel or extension tube other than rifling & chambering.
-No compensators or muzzle brakes allowed.
-You may use electronic triggers, if the entire assembly is firmly attached to and contained within the action or stock of the rifle, the trigger is operated by your right hand if you shoot right-handed (and vice versa), every part of it is present when the rifle is inspected, and if it doesn't cause the rifle to be oversized or overweight (duh).
-Slings: Maximum width 40mm (1.57"); may only be used on upper part of non-trigger arm and from there go to the forend, attached at a single point; may only pass along one side of the hand or wrist; may not touch the rifle except at the swivel and hand stop.
-Butt plates may be adjustable up/down, left/right, but may not swivel.
-Prohibited stock features: thumb hole, thumb rest, palm rest, heel rest, spirit level, grip-increasing material.
-Barrel weights may be used within a radius of 30mm (1.18") from the center of the bore, and may be moved along its length.
Obviously, there's a lot to consider... and I ain't done yet! The next section of this article discusses rifle sights. Rifle dimensions are too complex to list here, and may be obtained from USA Shooting (USAS).