By Christopher R. Bartocci
Since the 1960s, the 5.56x45mm caliber battle rifle has taken over the battlefields of the NATO countries. Many countries have adopted this caliber and adapted their own assault rifles to fire it. But in all the different assault rifles to fire this round, the M16 remains the number one 5.56mm rifle and is undoubtedly the most combat proven 5.56mm battle rifle in the world. Since its inception, billions of rounds and countless man hours have been spent to make it the rifle it is today.
In the intervening years since the 1960s there have been but only a small handful of military-specification manufacturers. Colt was the sole source producer of AR-15/M16 series rifles during the first part of the Vietnam War but as the war progressed, the military decided it was critical to have more than one source. Thus, limited contracts were given to Harrington and Richardson and the Hydromantic Division of General Motors. With the introduction of the Colt M16A2, the players would solely be Colt and FN Manufacturing, Inc. However, Colt would be the sole source contractor of the M4 and M4A1 carbines to the U.S. Government. Colt has only licensed three other producers the rights to manufacture their M16 design. The first was the Elisco Corporation in the Philippines and the second is in Singapore to build M16A1 rifle. The third is the Canadian Government.
In the early 1980s, the Canadian military decided it was time to update their arsenals with a new weapon system. They wanted a true assault rifle to replace their aging C1 and C2 rifles, which were a Canadian version of the 7.62x51mm NATO caliber FN FAL rifle. So began the SARP (Small Arms Replacement Program). The Canadians looked at several rifles including the MN1 Galil, FN FNC, M16A1, HK33 and others. The two finalists were the FNC and the M16A1 and the rifle ultimately chosen by the Canadian Forces was the Colt M16A2 rifle. However, they were not satisfied with the standard M16A2 rifle. Perhaps a more practical view for Canada’s military needs was to come from those forces themselves, rather than the new product improved M16A2.
After negotiations, the Canadian Government obtained a licensing agreement from Colt to begin production for the Canadian Forces and Colt provided the Canadian Government with their proprietary Technical Data Package (TDP) for the rifle. This contains all the drawings, specifications and production methods required to produce the rifles. The Canadian government had no military-run arsenals for small arms development or manufacture and the private firm Diemaco, a division of Heroux Devtek, was awarded the manufacturing rights of the new Canadian rifle. Diemaco, located in Kitchener, Ontario is a 48,000 square foot facility employing 120 to 180 employees that have been involved with firearms manufacture and overhaul since 1976. Diemaco has full automation capability including CAD/CAM, CNC machining, a research and development department, testing and evaluation departments, as well as a technical support service including training, documentation/manuals and training aids. In due course, Diemaco ultimately learned much more was to be required of them than to just get to work on production. The design firm was to do much development work to customize the M16A2 for Canadian Forces needs.
The C7 and C8
The designation for the new Canadian weapons was to be the C7 rifle and the C8 carbine. The prefix “C” simply stands for Canadian. The C7 would appear to be an M16A2 but upon closer examination there are many changes.
The Canadian Forces opted to not adopt the fully adjustable rear sight assembly. They decided that the windage adjustment only A1-style sight was much more practical for a combat rifle than the target sights the U.S. Marine Corp requested for their M16A2. Many of the other U.S. Forces felt that the Marine A2 style sight was too complex for a combat sight. Therefore, the Marine Corps is to this date the only branch of the U.S. military who trains to use it. The end result is that millions of dollars were spent on a complex rear sight that only a small percentage of US armed forces train their troops to use. The Canadian forces wanted a more homogenous sight use and training regimen.
Another big departure was that the Canadians decided against the 3-round burst mechanism in favor of the fully automatic setting. There are many reasons that the AR15 system was desired by the commanders of the troops in Vietnam. Among them were increasing the ammunition carrying capacity of the average soldier, and the differing wound ballistcs tests that still spark controversy today. The practice of “Spray and Pray” firepower with these 5.56 caliber weapons was considered an enormous waste of ammunition, and in the M16A2 JSSAP program, it was decided by some factions that a burst limiter should be in the weapon. This is the “Three-round Burst” in some current military use. The Canadian forces chose a view that burst limiting is an option the serviceman should have, but it should come from training, and not limit his options for fully automatic fire in combat.
The Canadian Forces also have a tradition of having adjustable rifle stocks to compensate for larger as well as smaller shooters. The C7 would utilize a short and an A1-legnth stock and have a spacer that can be fit to either to provide four sizes so as to customize the stock length for larger shooters. Diemaco redesigned the A2 handguards to have interlocking notches to strengthen the handguards and to make them more durable for being dropped and during the rough handling of drill and ceremonies.
The C8 carbine was merely a carbine version of the C7. The only changes are the thinner 14-1/2 inch carbine barrel and the sliding buttstock. Like the American Forces, the day of the carbine would be left until the mid-1990s.
Production of the C7 series was carried out in 5 phases over two years. Each phase was made to put manufacturing and logistics of the weapon components in Canada. Early phases had many parts manufactured or supplied by Colt. Towards phase 5, all parts would either be manufactured at Diemaco or by a Canadian sub-contractor.
Cold Hammer Forged Barrels
Traditionally, the barrels manufactured by Colt and any other mil-spec rifle are button cut rifling: meaning the rifling is actually cut into the barrel during manufacturing. This is per the TDP and is mandated for all U.S. military production M16-type weapons. However, Colt had looked into the possibility of cold hammer forging the barrels. After consideration, the cost of the hammer forge itself was prohibitive. At the time Colt was looking into this process, the barrels could not be manufactured that would meet the current accuracy requirements. The U.S. military was not interested in it without major research and development.
When Diemaco went into production, they felt that the hammer forging process was better for their needs. They believed that by this process they could increase the longevity of the barrel as well as increase accuracy.
Cold hammer forging is a process where the carefully selected ordnance steel stock is cut to length. A pilot hole is drilled through the center of the blank and the blank is then placed on a table on the hammer forge platform. A robotic arm picks up the blank and feeds it into the hammer forge. A mandrel is pushed through the pilot hole through the center of the barrel. The mandrel is approximately five inches long and contains approximately 3 inches of rifling plus the chamber. The mandrel costs approximately $7,000 and can manufacture between 7,000 and 8,000 barrels. When the hammer forge begins, 4 hammers exert 140 tons of pressure on the outside of the barrel blank at 1,000 strokes per minute. As this process progresses, the mandrel is positioned under the hammers in the barrel forming the inside of the barrel bore. As it reaches the end of the process the mandrel moves forward and the chamber is formed. When completed, the final barrel is approximately 50% longer than it was when it first went into the hammer forge. The early hammer forge used by Diemaco was extremely loud and shook the building. Over the last couple years it was replaced by a new one that you hardly need to wear hearing protection when it is making barrels.
There are many benefits to this cold hammer forging process. The first is repeatability. Every barrel that is manufactured from the same mandrel will have identical internal characteristics. There is significantly less changes in internal characteristics than in a tool changing every time it cuts. The second is enhanced accuracy. Cold hammer forging permits much greater concentricity of bore and chamber as opposed to a chamber that is drilled separately from the bore. Due to this process, the choke is controlled which impacts the release of the bullet from the muzzle. In essence, the bore diameter decreases the further down the bore the bullet travels. This increases velocity and accuracy while standard button cut barrels maintain the same bore diameter the entire length of the barrel. The third advantage is the strength of the barrel will be enhanced over conventional barrels. During cold hammer forging, the barrel aligns and compresses the steel molecules very tightly thus hardening the steel without the need to heat the barrel up to transformation temperature. This greatly affects the chances of avoiding brittleness. The fourth benefit is the surface quality of the barrel. Hammer forging produces “striations” that are longitudal and minor compared to chatter. This produces smoother surfaces on the lands and grooves. Additionally, the edges of the lands are not sharp, but are rounder. By having no sharp edges to wear, accuracy is maintained significantly longer. This is extremely beneficial on machine guns. Most of the models manufactured by Diemaco are hammer forged with a 1 turn in 7 inch twist. Diemaco has made barrels in 1:9 and sold barrels in some Custom Tactical (CT) rifles in 1:8 twist made by others.
The Canadian Polymer Magazine
The Canadian military felt there was a better way to produce magazines than the current aluminum magazines in service. In the mid 1980s, polymers began making an appearance in the firearms industry. With the onset of the M16A2 program, better materials were found that increased the durability of polymers and in some cases exceeding their metal counterparts. In some ways, synthetic materials are truly better. Plastics are impervious to shock and climate changes and, most importantly, they will not corrode.
The Canadian Forces adopted the Thermold magazine and Diemaco went on to refine and manufacture the new magazine. This would be a black synthetic 30 round magazine and were made of glass filled Zytel ST nylon. The first attempt did not meet with success. Issues arouse with the magazines breaking in the feed lips as well as the seam where the two halves were brought together. The Canadian military rejected them in favor of Teflon coated aluminum magazines. The second attempt in 1990 met with success. Main changes were in the mold itself and to the follower. Additionally, the feed lips were thickened and there is now a machine cut on the top side of the magazine lips which assist in feeding. These magazines will be identified by the mold code on the magazine. The year code may be found on either side of the magazine. Any magazine made prior to 1990 should be discarded. Many of the foreign contracts that Diemaco received utilize the current production polymer magazine. The magazines are still produced from Zytel by Dupont. This is the same material used in the pistol grip and buttplate of the M16A2 rifle. These Canadian/Diemaco magazines are not to be mistaken with the commercially produced Thermold magazines. These magazines will have the Canadian maple leaf on the bottom left or right side of the magazine. Diemaco claims these are just as reliable, and in some cases superior to, the aluminum magazines currently in use throughout the world. Diemaco never produced 20-round magazines.
Part two of the series Diemaco: The Canadian M16 will introduce the second generation C7/C8 series rifles and carbines; the C7A1/C8A1 flat top upper receiver. There will also be detailed descriptions of the expanding Diemaco family of weapons including the C7A2 Mid-Life upgrade, the CQB, SFW, SFSW, LSW and the CT as well as a description of other lands where Diemaco weapons are in service.
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