I am not a fine details expert on the C7/C8/C9 family, nor do I play one on the Internet. However, I have some familiarity with them.
If you’re focused on “the most common versions” currently in the CAF, the C8’s have been caught betwixt and between with the three program upgrades from the original C7/C8. Including the mid life crisis upgrades made by Regiments as they first deployed to A’stan i.e. the on the fly mods the PPCLI did with their weapons. Most Canadian Small Arms Instructors couldn’t tell the difference between a C8SFW and C8A3. And they probably wouldn’t care. The picture you have of the C8A3 is fairly accurate, minus the STANO kit usually found on those rifles overseas.
The C8A3 is/was more commonly seen with the Leitz C79 optical sight that is issue for the C7A2 as well. Fantastic glass, especially in low light light conditions. Originally had a lot of problems with a wandering zero due to poor planning on the mount portion of the sight, but the changes in the latest versions seem to have fixed that. Any surplused C79’s that made it to the civilian market will probably have the original mount - as well as a tritium element in the tip of the aiming post that is dead. And it will probably cost around $2000… which will almost certainly make the Eotech look better and better all the time.
Reference the handguards, if you snoop around on the Internet, you’ll find the Canadian Technical Data Packages for the 200+ design changes Canada made to the M16 they licensed. I found it on some obscure Canadian government bureaucracy website. Some very minor changes, some not so much. One of the changes has to do with the type of material used to make those handguards, which Diemaco called Fiberlite if my memory doesn’t fail me. That had to do with extreme cold weather testing for the rifle, down to -70 or something like that.
Original furniture is occasionally available at the Canadiangunnutz website’s buy and sell section. If you offer the magic amount of money for it, somebody will decide they don’t actually need genuine Canadian furniture after all. If you go to their AR15 sub-forum, you’ll find a lot of info on guys attempting to build replicas just as you are, so you should be able to see where they sourced the parts they used. I think a few people from Diemaco/Colt Canada actually hung around there answering technical questions, at least they did for a while. Canadian military will have a pebbled finish to the Fiberlite furniture.
A business that occasionally sources genuine Colt Canada military parts are these guys: http://www.nordicmarksman.com/C7A2-C8A3-CF-Green-Butt-Plate.html
They will certainly sell you the POS ambi charging handle that seems primarily designed to snag on any equipment on your chest that isn’t perfectly smooth and without openings… a fair number of guys buy a charging handle of their choice and switch out the HookMaster when they draw their weapon from the QM. This is what you get when gun plumbers get involved in weapons design and the guys in combat arms who actually have to use the weapon get kicked to the curb. Which is why the eye relief of the C79 was such a problem before the collapsing buttstock on the C7A2 arrived, incidentally… and why they probably designed the HookMaster, because everybody without a giraffe length neck had to mount the C79 at the very back of the upper receiver to get proper eye relief - and where it overhung the charging handle and got in the way of grasping the charging handle.
http://www.nordicmarksman.com/C7A2-C8A3-CF-Ambi-Charging-Handle.html
One thing you don’t mention is the barrel. It’s hammer forged and 15.7" in length. Diemaco fired about a bazillion rounds through the barrel contour they were going to put on that rifle and determined that 15.7" was the magic number for greatest accuracy out of mass production barrels. Don’t quote me on this, but I think the Brit MOD who was buying those for the SAS at the time funded all or some of the testing that was done to wring the best accuracy out of that barrel. So you could mount a 16" barrel and I doubt anyone will notice you’re about .3" too long. Something like this would be a pretty close replica to the barrel with the Simon Sleeve (not planning on mounting a Canadian POS M203, are you?): http://www.bravocompanyusa.com/BCM-Standard-16-C8-SFW-Upper-Receiver-p/bcm-urg-c8-sfw-16.htm There may be others that are closer replicas… again, I’m not a details guy.
Your front sight should be round, not square, measuring .050". I think it was Rock River that originally offered an identical front sight… me likee.
The C8A3 has a shorter Triad than the C7A2 to accommodate the POS M203
Markings for the fire selector switch on the lower receiver would be different i.e. “S” and “R” and “Auto” with the automatic marking missing… I don’t know how you would address that short of an 80% receiver and then a custom engraving job. If you did that, the world would be your oyster and it would look REALLY identical.
You’re missing the short Cadex picatinny rail mount attached by way of the holes in the handguard, usually used to mount the Cadex folding pistol grip. Some Canadian troops mount the pistol grip, just as many don’t.
Can’t think of anything else at the moment. You’ll find hours of details concerning your replica build up at Canadiangunnutz, from guys who actually are details experts. I think a member named KevinB over there is about as authoritative on all things C7/C8 as you could ask for.
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