https://thecmp.org/wp-content/uploads/Rulebook.pdf6.1.1 M16/AR15-Type Rifles The rifle must an M16 U. S. Service Rifle or a similar AR15-type commercial rifle that is derived from the M16 service rifle design. The following specific rules apply to this type of rifle:
Must be chambered for the 5.56 x 45 mm NATO (.223) cartridge.
Must be designed or modified so that only semi-automatic fire is
possible.
The gas operating system must be fully operable and adhere to the original M16 rifle design (i. e. Stoner design, gas impingement system) or have a piston-operated gas system.
The receiver and handguard must be machined as separate parts.
The barrel may be no longer than the standard A2 barrel length of 20 inches (20 3/8 inches if measured from the back of the barrel extension); flash suppressors are not required, but if the barrel has a flash suppressor, the total length of the barrel, measured from the back of the barrel extension to the target end of the flash suppressor shall not exceed 21 5/8 inches.
Quad rails or similar hand guards may be used. The front sling swivel may be attached to the hand guard, but must be fixed and located 13.25 in. (+/- 0.5 in.) from the forward edge of the magazine well on M16 configured rifles or 8.0 in. (+/- 05 in.) on M4 configured rifles.
Upper receivers and/or barrels may not be changed during the firing of any event.
The trigger pull must be at least 4.5 pounds.
Metal or synthetic (polymer) magazines, standard issue or commercial equivalent, with standard service 20 or 30-round box magazine dimensions must be attached during the firing of all courses and in all positions. A 10-round magazine with the same external dimensions as a standard service 20-round box magazine may be used. A dummy magazine with a ramp for single shot loading may be used if this magazine has the same external dimensions as the standard service 20- round box magazine.
The rifle may have an optical sight (reflective sights are considered optical sights) with a maximum power of 4.5X installed on the receiver. Variable scopes with a maximum of 4.5X are permitted. Only commercially manufactured scopes that were produced with a maximum magnification of 4.5X and that have a maximum objective lens diameter of 34 mm may be used. If an optical sight is used, the same optical sight configuration must be used in all stages of a course of fire (changing sights or sight mount configurations is not permitted). The centerline of
an optical sight shall be no higher than 3.5 inches above the centerline of the bore.
Alternatively, the rifle may be equipped with issue-type metallic front and rear sights with a maximum sight radius of 20.5 inches. Metallic sights, if used, must have an M16 type sight design with the rear sight in the carry handle and the front sight in the standard M16 location.
Butt-stocks may vary in length and be either fixed or collapsible. Collapsible or adjustable length stocks may be adjusted during an event, but butt stocks that allow for other adjustments such as the cheek-piece height or butt-plate location may not be used.
Only standard A1 or A2 type pistol grips may be used.
An extended bolt release is permitted.
Left-handed receivers that reverse the operational design features of M16/AR-type rifles are permitted
now allow this:
go distinguished with it!