Editor’s Note: Subsequent to this article being written, it should be noted that Colt Defense LLC has purchased the Logistics & Defense Division of Heroux-Devtek, Inc., which includes Diemaco. Diemaco will be operated as Colt Canada Corporation, a wholly owned subsidiary of Colt Defense. – Robert G. Segel

As production of standard C7 and C8 weapons went on, it was decided by the Canadian Forces that they wanted to have a platform to enable them to mount optics on the weapons. Traditionally, it has been very uncomfortable to mount a scope on an M16 rifle due to the height of the scope on top of the carrying handle. Not only was it an unnatural way to shoot, it exposed more of the shooter’s head than was desirable. This upgrade was not to be just for specialized units, but for the entire fleet. The Canadian Forces were about to equip every weapon with an optical sight.

Diemaco went to work on the development of an integrated flat top upper receiver. The Canadians decided on a modified Weaver rail that does not conform with the American Mil-Std-1913 rail for one clear reason, it did not exist yet. Their research and development pre-dated the adoption of the mil-std-1913 rail. Numerous methods to attach the rail were tested including (vacuum bonding) gluing it to a modified upper receiver – but for obvious reasons the preferred way would be to have it machined out of a single forging. It took a couple years to finalize their design. Richard Swan, of ARMS, Inc. was called in to assist with the design of the dovetail. ARMS has had many years of experience in the design of dovetails and many were in use by American Forces.

The C7A1 and C8A1

The new weapons would be type-classified as the A1 variations of the C7 rifle and C8 carbine. Canada did not convert C8’s to C8A1 until quite recently. Diemaco used the term A1 to identify carbines with flat top receivers used in other countries such as Holland. The Danes call their C8A1 the M96 Karbine. These weapons would enter service before the Colt release of the Mil-Std-1913 rail. This was a conversion process to existing C7 rifles and mandated for all future small arms production. The standard rifle and carbine barrel assembly would be used without modification. This enabled current C7 and C8’s to be converted to the new configuration by just replacing the receiver itself.

Diemaco also designed two different iron sight capabilities. The first is a primary iron sight, which is a removable carrying handle similar to the Colt designed removable carrying handle on their M16A2 Enhanced rifle and their ACR candidate. This carrying handle would maintain the standard adjustable for windage only rear sight. Additionally, an emergency back-up sight was developed that would serve as a back-up if the optic was to become damaged and inoperable. The final design was made of nylon ST super tough plastic and would mount in front of the optic.

The optic chosen by the Canadian Forces was manufactured by another Canadian firm, Armament Technologies who had also designed an optic for Colt during the Advanced Combat Rifle program. These sights were first designed by Ernst Leitz Canada, which made Leica Cameras, heavy gun and tank sights, and other equipment that required quality precision optics. The company was purchased by Texas Instruments and renamed ELCAN Optical Technologies. It is now owned by Raytheon. The C79 optical sight was an extension of a program for a sight intended for the old C1A1 FAL rifle, updated for the C7A1. The United States forces now uses this optical tube assembly in the M149 sight that they now use. ELCAN also makes all IMAX and PANAVISION camera and projector lenses, inertial guidance muti-facetted mirrors for Maverick missiles and many other military optics. This firm employs about 600 people grinding and coating optics and manufacturing mounts making every kind of optical, night vision and thermal equipment imaginable for military and civilian applications.

The C7A2

In 2003, the Canadian Forces implemented a mid-life upgrade to the C7A1 and C8A1 weapons that included being more compact, versatile and ambidextrous as well as better suitability to accept new attachments such as laser sights, flash lights, etc.

The C7A2 would omit the fixed stock. All weapons would utilize a telescopic dark green stock with 4 adjustable positions and an anti-slip butt pad enabling the rifle to be more compact to carry. With this switch, a new buffer was used which is identical to Colt’s “H” buffer that replaced one of the standard steel weights with a tungsten weight. This additional mass eliminated light strikes caused by the bolt carrier bouncing back off the barrel extension during automatic fire. A dark green pistol grip replaced the black one.

The upper receiver is the standard flat top upper with the 20-inch barrel. This was left in the 20 inch length for a simple reason; to maintain the ballistic capability of the NATO standard 5.56mm ammunition it was expected to employ. By maintaining the long barrel, the cyclic rate is reduced from the carbine variations and increases reliability due to a lower cyclic rate. This also extends the life of the bolt and other trigger components. If the weapon was to be reconfigured from the C7A1, the upper receiver would be left alone but would have new dark green handguards installed with a Triad 1 attached to the front sight assembly. The Triad 1 offered left, right and bottom rails that enabled the attachment of laser, flash lights and other equipment.

The other main improvement was making the weapon as ambidextrous as possible. The ambidextrous magazine catch was designed by another firm (NORGON) and Diemaco obtained a licensing right to produce the catch assembly in the factory. Other improvement features included an ambidextrous charging handle release lever and selector lever.

The LSW (Light Support Weapon)

The LSW began life as a Colt design of a light support weapon based on the M16 weapon system. This open bolt firing version was designed by Colt’s engineer Henry Tatro. The Colt design was never able to leave the development stages due to a labor strike and inability to free up resources to get a new project off the ground. Diemaco was called in to see if it was a project they were interested in and if they would have the resources to complete the project and get it ready to sell. Diemaco was a perfect company to take on this project due to their engineering capability and relatively small size.

Diemaco made some improvements to the open bolt fire mechanism and updated the design with some of the new M16A2 features including the new stock, pistol grip and lower receiver as well as new fully adjustable rear sights. Diemaco would also make major improvements to the barrel assembly utilizing an extra heavy hammer forged barrel, redesigned interchangeable handguards, a large foregrip that can be used as a monopod, a QD bipod, and a redesigned carrying handle. Diemaco additionally redesigned the gas tube to a larger diameter to deal with the heat of an extended firing weapon. Diemaco also put the finishing touches on a Colt designed hydraulic buffer which slowed the rate of fire down to less than 700 rounds per minute. Diemaco has sold this weapon to customers including Denmark and Holland. This weapon is made in both fixed carrying handle and flat top variations. Diemaco has also produced this weapon in a closed bolt selective fire configuration as requested by the Royal Dutch Marines and Denmark.

The SFW (Special Forces Weapon) Diemaco’s Crown Jewel

The British Special Forces began a search for a weapon that would replace their problematic SA80 assault rifles, holding trials for a potential replacement. Three of the finalists were the Heckler & Koch G36, SIG 500 series rifle and the Diemaco produced SFW (Special Forces Weapon). Because the British Army would not accept contractors who had been in bankruptcy within 10 years, Colt was disqualified from the trials. The winner was the Diemaco SFW. This was only the starting point. The weapon that would be supplied to the British Special Forces would be a highly customized and refined carbine.

Based on the accuracy requirement, it could not be made with a 14-1/2 inch barrel. In order to maintain accuracy, Diemaco produced a 15.8 inch heavy barrel. The barrel was heavy only between the chamber and front sight to provide a rigid mounting platform for add-ons and a greater heat sink for sustained firing. Furthermore, the heavy section and addition of a front barrel sleeve changed the vibration modes of the barrel when firing. Part of the requirement was light weight; however there was a trade off for accuracy that enabled the required accuracy to be met. There was another benefit: an increase in terminal performance over the 14-1/2 inch barrel. By increasing the velocity from 865m/s of the shorter barrel to the 895m/s of the SFW barrel there was an increase in penetration, range and terminal performance. The SFW were also equipped with a KAC RAS system.

Another modification was made based on the type of grenade launcher used. The British Special Forces use a Heckler & Koch grenade launcher that attaches to the bayonet lug. It was found that with use, the taper pins would either fall out or snap. When the front sight assembly was replaced, it would crack. Diemaco redesigned the front sight assembly to be made of a solid forging to increase the strength to deal with the grenade launcher.

This version has been sold in other configurations as well to other military and law enforcement customers. They may be found with standard handguards and standard front sight assemblies as well. An additional model is the SFSW (Special Forces Support Weapon) which has an even heavier barrel designed for the increased firing schedule. These come equipped with a RAS, vertical pistol grip, FAL-style carrying handle, bipod as well as a hydraulic rate reducing buffer (similar to that used in the LSW).

The C8CQB (Close Quarters Battle)

Many special operations units, both military and police, spend a lot of time in urban environments in close quarters scenarios. These include entries into buildings and caves which make longer barreled weapons clumsy and hard to move under cover and around corners. To answer this demand, Diemaco added another member to their C8 family of weapons, the C8CQB. This utilizes a 10 inch barrel with a Vortex flash suppressor. Other than the shorter barrel, it is identical to the rest of the C8 family of weapons. This is the only weapon that Diemaco puts in the rubber “D” ring extractor insert to increase extractor force to aid in reliability and may be equipped with a silencer (suppressor) as well. On these small entry guns the optic of choice is the reflex-type sights such as the Eotech holographic sight or the Trijicon ACOG reflex sight.

The C7 and C8 CT (Custom Tactical)

Many accurized versions of the AR-15/M16 weapon system are available at this time. The most notable being the Mk12 MOD 0/1 rifle in use by the United States Special Operations Command. Due to the inherent accuracy of this weapon system, it is possible with little effort to get a match grade barrel and have it shooting sub-moa at 100 meters. This degree of accuracy has both military and law enforcement applications. Diemaco produces two basic versions of accurized rifles/carbines.

The C7CT (Custom Tactical) is a highly modified C7A1. This rifle has a 20-inch heavy non-chrome lined, hammer forged barrel with an aluminum free floated barrel handguard. The barrel is designed to take a removable noise/flash suppressor very similar to that of the Mk12 MOD 0/1. To enhance accuracy, the rifle has a two stage trigger and titanium firing pin. The upper receiver has a flat top upper receiver with either a mil-std-1913 rail or the Canadian Weaver rail. Often the scope is attached to a Triad scope base to allow other devices to be attached. The buttstock is fitted with a removable weight to counter balance the additional weight of the heavy barrel. A bipod and sling swivels are also standard equipment. Additionally, a modified pistol grip is used to enhance performance. The maximum effective range with Canadian C77 ball ammunition is approximately 600 meters.

The C8CT is the carbine version which offers the same benefits but with a 16 inch barrel and a telescopic stock. The stock is modified with an adjustable butt pad. Due to the shorter barrel the maximum effective range is 400 meters.

Conclusions

Although not available in the United States, Diemaco produces one of the finest M16-type weapons in the world. What truly sets Diemaco aside from the rest of the manufacturers of this weapon is their diversity and ability to customize to the customers’ specifications. The weapons covered in these pages are but a small sample of what Diemaco produces. Many variations have been made at the request of their customers. Diemaco has taken the standard M16A2 and moved ahead with refinements and modifications of their own design.

Due to the Canadian Governments licensing agreement with Colt, the market place for Diemaco is limited. However, this is a company to be taken very seriously and if available to a customer, should be looked at very closely.

The author would like to thank Matt Kirkpatrick, Kelly Stumpf and Ian Anderson of Diemaco for their assistance with this series. Additionally, Mr. Andrew Weber of Armament Technology.

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.