There are those out there that would have you believe the AR-15 is the very latest in firearms technology. Billed by media outlets and politicians alike as a bleeding-edge military development project only slightly less advanced (and lethal) than the F-35 Lightning II fighter jet, there are plenty of AR-15s out there on the market today that certainly look the part, but the reality is that the overall rifle is simply old. Designed in 1957, its foundation is more Avro Arrow than F-35, and by and large development on the platform has been evolutionary rather than revolutionary.
And there’s a good reason for that. Eugene Stoner’s basic design was so good that it has simply proven quite difficult to thoroughly improve upon. Sure, there are all sorts of whiz-bang piston-driven options out there and we’ve turned accessorizing your AR-15 into a sort of adult form of Meccano, but if you take the furniture off and reduce most modern AR-15s down to their most basic parts there’s little to distinguish them from the ones Armalite was making over 50 years ago.
All that being said, when you put that rifle back together, the manner in which it will be used and the degree to which it will be expected to perform today are much different than the expectations placed on the rifles of yesteryear. Pencil barrels, gas block front sights, and carry handle-cum-iron sights were considered cutting edge, largely due to the US Army’s shift away from low volumes of aimed fire, and towards high volumes of directed fire in Vietnam’s dense jungle. But just as the military’s demands gave Stoner the framework upon which the original AR-15 design would be hung, the modern military’s demands are again changing the rules; demanding what would have been considered match-grade accuracy in 1957, and requiring compatibility with magnified optics and integrated night vision solutions. Vertical foregrips or other such devices are everywhere, and many would consider the absence of a flashlight on a handguard to be downright irresponsible. Add in the various sling attachment options available, bipods, and light/IR/laser combinations preferred by the world’s developed militaries and you end up with rifles that have a whole lot more stuff hung off the front of a rifle that is all designed to extend the operability and usefulness of the modern carbine. But many AR-15s have not changed their overall design to reflect this new reality.
Which brings us to the Colt Canada Integrated Upper Receiver; better known colloquially as the Colt Canada IUR. One of a relatively small subset of rifles designed with what’s known as a monolithic upper receiver, the IUR’s name should give it away; the rifle has the handguard integrated into the upper receiver forging. This has a few obvious benefits. First, it means the topmost rail is uninterrupted and more stable than any other style of handguard, which can be beneficial to military personnel looking to mount in-line night vision optics and target designators. For civilians, it negates the need for cantilevered scope mounts, and allows any forward-mounted sighting systems (such as 45-degree offset red dots and the like) to mount to a rail that is guaranteed to be true to the bore. Secondly, and perhaps of even more importantly, it means the barrel is truly free-floated. On conventional handguards the front of the handguard is affixed to the barrel near the gas block, meaning and pressure placed on the handguard is directed into the barrel, which can change the point of impact.
The Colt Canada IUR Family
The Colt Canada IUR family of rifles has three distinct generations; the first being identifiable by virtue of its aluminium-lined glass fibre “side doors” on the handguard. These doors can be removed and allow the barrel to be installed and removed with a short, but specialized, barrel nut wrench (this is similar to the system employed by Colt USA’s 6940 monolithic rifle). Furthermore, it used a standard gas tube, and a conventional extension so that any C8 barrel might be used. Due to the rifle’s varied popularity (it was accepted into service with both the Dutch military and Corrections Canada) and the variety of ammunition it would be expected to digest, M4 feed ramps were used to ensure reliable feeding with frangible, ball and all commercial ammunition. Finally, the first generation Colt Canada IUR rifles typically used conventional gas block front sight forgings, or used folding front sight gas blocks.
The second generation of Integrated Upper Receivers abandoned the detachable hand guard “side doors” in favour of a single forged piece. Of course, this meant the barrel needed to be secured via a much longer barrel nut socket, which reaches down the length of the handguard. Needless to say, you won’t be removing the barrel from an IUR rifle with your standard AR tool. Next, the second generation did away with the conventional or folding front sight gas blocks, replacing them with low-profile gas blocks affixed to the barrels secured by tapered pins. Steel inserts were manufactured and inserted into the area where the charging handle latched in order to extend service life. Finally, a straight gas tube was used to increase durability and ease of maintenance. In order to reduce the receiver’s weight, a generation 2.5 format was created, wherein additional material was removed from inside the handguard and around the vents. To date, there have been over a dozen variants of this second generation Colt Canada IUR produced for various contracts, and while the existence of a third generation is confirmed, no additional details have been released.
Now all that being said, while there may be over two dozen different versions of the current generation Colt Canada IUR, the upper receiver pictured here is the first and as-yet only style of Colt Canada Integrated Upper Receiver that has been released to the public. These are actually overruns of a production run of second generation Integrated Upper Receivers destined for the Danish military. Let’s say that again: These upper receivers aren’t replicas of those found on Danish military rifles nor were they built to be similar to the Danish pattern rifles; they are literally left over upper receivers manufactured by Colt Canada that were surplus to the Danes’ needs. That makes these, technically, military surplus upper receivers!
While all Colt Canada IUR rifles consist of the same forged, monolithic upper receiver, the Danish models specifically differ from the “standard” IUR rifles in a couple ways. The most obvious change is the heavily machined handguard assembly. While standard IUR receivers feature full-length NATO-standard rails on all four sides, the Danish rifles have had the side rails milled off of the latter half of the handguard, leaving just the sling quick-disconnect socket. That helps remove some of the weight from the front half of the upper receiver, where the legitimately portly IUR receiver carries a significant amount of its mass due to the barrel’s heavy profile. The other departure from the standard IUR format is affixed to the end of that barrel, where Colt Canada has fitted the flash hider from the C9A2 light machine gun; a unique flash hider of Colt Canada’s own design that reduces visible flash by 30%. It is also directional, and is designed to direct no flash up into the sight picture, and no gas down towards the ground.
The Heart of the Matter
Like all Colt Canada rifles, as smartly designed and well-made as the Integrated Upper Receiver is, the key component remains the barrel. Cold-hammer forged in a single process that forms the rifling and the chamber together, the bore is guaranteed to be perfectly concentric to the chamber; a claim that is impossible to make if the chamber is cut on a lathe after the rifling is formed. Furthermore, that process by which the 15.7” heavy-profile barrel of these rifles are made also requires some substantially better steel than most manufacturers use, as the hammer-forging process forming the chamber and rifling must turn a large-bore blank into both a small-bore barrel and relatively large chamber all in one pass without warping or bending as it moves out of the hammer forge. Hence, the raw steel barrel blanks used by Colt Canada actually cost more than a finished Colt USA barrel, which are made by button-rifling the bore and cutting the chamber separately. Of course, these barrels are also chrome lined, and feature the usual 1:7 twist rate you’d expect.
So it should come as no surprise then that the combination of a Colt Canada heavy barrel in a monolithic receiver that allows it to be truly free floated is one seriously accurate package. As we discovered when we tested the SA15.7 and SA20 series of rifles, the 15.7” heavy barrel is ridiculously accurate due to both the work that goes into its production and the native harmonics of the specific barrel length, and the rifle pictured here easily delivered upon Colt Canada’s claim of sub-MOA accuracy. Shooting a variety of 55-grain bulk, and some 62- and 69-grain match ammunition, rewarded us with 5-shot groups ranging from 1.55” to 0.88” across at 100 metres. The only exception? Some leftover Norinco 5.56 ammunition we had that seemed to throw itself at the paper in a very disappointing fashion, printing terribly inaccurate groups that were never smaller than three inches. In the interest of full disclosure, as this was to be a test of the upper receiver, we used a Caldwell Lead Sled to stabilize the rifle during testing, and had the upper pinned to a Colt Canada receiver stuffed with standard USGI components. As our Colt Canada IUR was received sans bolt assembly (as most are) we borrowed a standard semi-automatic bolt carrier from one of our other AR-15s to complete the job.
Shooting offhand, the Colt Canada IUR still provided amazing accuracy if we did our part, but did prove to be a relatively heavy rifle. In a world where sub-four pound commercial AR-15s are a reality, the beefy barrel and handguard assembly of the IUR is definitely closer to something you’d see in a military setting than many consumers may be used to, but that really shouldn’t come as much of a surprise as these technically are military contract upper receivers that were never built with the commercial market in mind. The IUR was designed to be carried and used by people that work in careers where an annual physical aptitude test is a job requirement. Hell, the little nub of aluminium at the rearmost section of the lower rail is a grenade launcher recoil lug. Think about that for a second.
In fact, the only other critique of the Colt Canada IUR we could find was specifically that recoil lug. Unless you happen across one of the lower handguard panels Colt Canada produced that covers the majority of the lug, it seems like it’s just asking to get dinged up, and when you take the rifle down you absolutely must be mindful of the recoil lug’s presence. If you let it, that lug will drive itself into the front of your magazine well when you’re breaking the rifle down, and if you happen to be in the habit of holding the front of the magazine well when you remove the rear take down pin you’re in for a world of hurt when that lug pivots down. Trust us. The best solution? Find a grenade launcher, obviously!
Dollars and Sense
But honestly, while the weight of the entire assembly and the hand-crushing risk posed by the grenade launcher lug are worth mentioning, those small issues take a very definite back seat to the fact that these upper receivers are turn-key sub-MOA assemblies. Furthermore, they are proudly made right here in Canada, and represent a unique opportunity for Canadian gun owners to own a little bit of Canadian heritage. Just as Inglis produced quality firearms for all manner of foreign fighting forces, so too does Colt Canada, and these Danish upper receiver assemblies are perfect examples of precisely how valued the Colt Canada name is abroad. But the best part is definitely the price: You can pick up one of these uppers for around $560. That’s $560 bucks to get sub-MOA accuracy, an awesome monolithic receiver, and the knowledge that your money is staying right here in Canada. To put that in perspective, a hammer-forged 16” barrel produced by FN carries a price tag of $500 Canadian, and requires an upper receiver forging, gas block and tube, muzzle device, and handguard. By the time all that is assembled the bill will have easily have surpassed a $1,000, making these upper receivers both some of the best-performing uppers on the market today, and also one the smartest buys you’re ever going to see. At least, we happen to think so, since we here at Calibre bought three of them ourselves.