In 1984, Canada decided to equip their military with a new rifle and wanted to go with the NATO standard cartridge 5.56x45 mm. In order to save development time and money, they decided to purchase the license to manufacture M16s of their own. A little while earlier, the US Marines were working towards improving the M16A1 model to the M16A2. A Canadian military liaison officer was also present while the Marines were working on improvements and he communicated some of these design changes back to Canada. As a result of this, the Canadian C7 rifle was developed with some features of the M16A1 and some of the M16A2. A Canadian company, Diemaco, was put in charge of manufacturing the new rifle.
C7 (top) and C7A1 (bottom) rifles
The C7 rifle has the stronger and longer stock, barrel with 1 turn in 7 inches twist rate, pistol grip and handguards of the M16A2, but retains the older rear sights of the M16A1, as well as the same firing modes of the M16A1 (single shot and fully automatic). One more major difference, which is not obvious, is that the C7 barrel is manufactured by the hammer-forging process.
The C7A1 incorporated some improvements to the C7, the main one being the replacement of the carrying handle, with a rail that allows the user to attach other devices here, such as iron sights or optics. This is similar to the M16A4 model, however the C7A1 preceded the adoption of the Picatinny rail by the US military, therefore the rail on the C7A1 is of slightly different dimensions than the now standard picatinny rails.
The C7 and C7A1 models are now being replaced by the C7A2 model in the Canadian military. The C7A2 has picatinny rails, in order to be standards compatible with all the accessories that are made to fit on a picatinny rail. It also has rails in front to attach laser pointers or lights. Unlike the previous models, it has a telescoping stock. One more major difference is that the C7A2 rifle furniture is green in color, instead of black. Other changes include ambidextrous magazine release and ambidextrous safety selector levers.
The C7A2 model rifle
The C7 family also comes with corresponding carbine variants, the C8, C8A1 and C8A2. The C7 and C8 families are used by the military forces of Canada, Netherlands, Denmark, United Kingdom (Special Forces mostly), Norway (Special Forces), Canadian Police etc. In 2005, Diemaco (the company that made the rifles in Canada) was bought out by Colt and is now known as Colt Canada.
Another manufacturer of M16 clones is Singapore's ST Kinetics, which produces the M16S1 for Singapore's military. The M16S1 is simply a M16A1 made under a license by ST Kinetics.
Another clone of the M16 family is the Chinese made Norinco CQ. Unlike the C7 family, the Norinco CQ is an unlicensed clone of the M16. While it uses the same 5.56x45 mm. cartridges of the M16, the Norinco CQ was never adopted by the Chinese military. However, they make two models for export, one capable of selecting between single shot and fully automatic fire for military sales and a semi-automatic only version for civilian markets.
Public domain image of a Norinco CQ rifle. Click on the image to enlarge.
It is pretty easy to tell a Norinco CQ apart from other members of the M16 family. First, notice the shape of the stock is completely different from the M16A1, M16A2, C7, C7A1 etc. Second, the handguards in front are also differently shaped than the other members of the M16 family. Thirdly, the pistol grip is curved on the Norinco CQ. Fourthly, the front sight on a Norinco CQ is of the hooded sight type, instead of a sight post.
The barrel of a Norinco CQ has a 1 turn in 12 inches twist rate. Because of this twist rate, it will fire the M193 cartridge designed for the M16A1 properly, but cannot accurately fire the NATO standard SS109 or the newer US M855 cartridge beyond about 100 meters or so (because these require a twist rate of 1:7 for stability in the air).
While the military version of the Norinco CQ was never used by the Chinese military, it is used by military forces of some other countries, such as Cambodia, Syria, Libya, Iran (which makes their own copies of the Norinco CQ), Sudan etc.