By Chris R. Bartocci
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.
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.
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.
|This article first appeared in Small Arms Review V9N3 (December 2005)|
and was posted online on March 29, 2013