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Author Topic: Building a Canadian C7 GBBR  (Read 13770 times)
Rob Bye
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« on: August 03, 2012, 12:54:47 pm »

The C7A1 assault rifle was the standard issue weapon of the Canadian Forces toward the end of the Cold War.

A Canadian soldier with his trusty C7A1

The C7A1 was an updated version of the earlier C7, but with an upper receiver featuring a built-in top rail that accommodated a C79 Elcan 3.4X optic sight.

* * * * * * *

Having previously used gas blow back rifles, I knew their realistic functioning ideally suited them to our mil-sim style of airsoft. No winding a high-cap magazine containing a full day's worth of BBs – a gas rifle is, instead, limited to whatever number of rounds their real-world counterpart is limited to. In the case of a C7, that's 30 rounds maximum.

Also, the firing action of a GBBR is much more realistic than anything you can ever experience with an electric rifle. When you pull the trigger on a gas rifle, there's a pronounced BANG!, and the gun's action cycles, just as it would on a real weapon, producing a fairly good amount of felt recoil. After the last round in the magazine is fired, the action locks back until you insert a fresh magazine and press the bolt release to chamber the first new round.

For my C7A1 GBBR build, I used an M16A3 from Taiwanese manufacturer WE-Tech as my starting point. I'd used WE gas rifles previously; in particular, their popular G39, which is an accurate, reliable, and authentic replica of the German military's HK G36.

To minimize the package size, WE-Tech ships their M16s separated into two halves, dividing the upper and lower receivers. All the user needs to do is join the two portions together, securing them with two pins retained within the lower receiver.

The rifle comes with one magazine and a loading tool. The loading tool holds about 15 BBs at a time, so you'll need to fill it twice for each standard 30 round magazine.

Gas magazines ship from the factory with pressurized air inside. Before using the magazine for the first time, be sure to purge that air by depressing the knocker valve, located at the rear of the magazine, near the top. Then, go ahead and fill the mag with green gas, or propane.

Take note: propane, by itself, is not the proper gas for a GBBR. You need to add a specific grade of silicone oil to the propane, in order for it to have the correct lubricating properties.

I use a fill adapter from Airsoft Innovations, a Canadian company. It's a plastic fill valve that screws onto the top of a standard camping size bottle of propane. Airsoft Innovations includes a small bottle of lubricant with each of their adapters. All you need to do is add two drops of lubricant into the the top valve of the propane bottle, screw on the AI fill adapter, then you're good to go. You'll need to add a couple more drops of silicone for every ten magazines worth of propane (roughly, every 300 rounds).

At one time, Airsoft Innovations machined their fill adapters from brass. They switched to plastic when it was discovered the brass fill nozzles can tear rubber seals around the magazine's fill valve. If you use an adapter made from brass, just be doubly careful while gassing-up your magazines.


I don't know if it really matters, but I always use Coleman brand propane. I've heard some of the other brands may have stronger propane odours to them. In time, you get accustomed to that propane smell, and you never really notice it while firing a gas gun outdoors, anyway.


Over the past year, I've fired thousands of rounds through my gas rifles, but I'm just now nearing the end of my third tank of propane. Compared to the costs of good batteries and a smart charger, it's likely cheaper to run a gas rifle than an AEG.

Gas gun magazines should always have some amount of propane stored within them. Pressure from the gas helps keep the rubber seals in good functioning order. The fill valve on a standard WE-Tech M16 magazine is located on the bottom of the mag. Dirt can easily accumulate around this valve, so be sure it's free of debris before adding more gas. One fill of gas should be enough for two full loads of BBs (i.e. 60+ rounds).

So, after giving my new rifle a thorough checking over, I got down to the business of test firing it.

I like to use a tree, located 60 meters away, as my test target. I optimistically aimed the new rifle at this tree, lined up the iron sights, still on their factory presets, and squeezed off the first round. I was very pleasantly surprised to see that initial BB bullseye the tree. To prove to myself it wasn't just a lucky fluke, I took a second shot, achieving a second dead-center hit.

“Not too shabby for a rifle, straight out of the box, using iron sights,” I smiled to myself.

That smile was quickly wiped from my face when I took a third shot, and the rifle literally disintegrated in my hands!

I'm serious! The gun completely fell to pieces after only firing three shots!

The stock snapped off and fell to the floor, the recoil buffer and spring went flying across to the other side of my shop, and the bolt carrier group was left hanging out the back end of the receiver.

I was utterly dismayed! What could cause such a catastrophic failure?

As it turned out, a crack had developed through the lower receiver, right where the buffer tube attaches. This is the point, where the weapon experiences most stress during firing, and plastic failed as a material for handling those kinds of forces.

In any event, rare as it may be, that type of failure was fatal to the gun. I already had a metal receiver on order, so I decided to shelve the project until it had arrived.

WE has two styles of metal receiver available, one with Colt M4 markings, the other with no markings whatsoever. The blank, unmarked receivers were intended for guns entering the U.S. market, where WE needs to avoid trademark litigation with Colt Firearms. I'd hoped to find one of those, but had to settle for ordering a marked receiver instead. If I ever lay my hands on a blank receiver, I'll sent it to Imperial Engravers in Toronto to have it laser engraved with Canadian Forces /Diemaco C7A1 markings and a late 1980's serial number. That would be the killer look for East Wind!

Once the new metal receiver arrived, I set about giving my rifle a complete rebuild. Just like a real M16, you need a good armorer's wrench to service these rifles. A good wrench runs about $30.

I had to disassemble the inner bolt/nozzle to install an NPAS valve. This device, made by RA-Tech in Taiwan, allows the user to tune down the gun's velocity. Once you get an NPAS-equipped gun dialed in, you can pretty much leave it alone. Only on a very hot day might you ever need to make adjustments to the valve. RA-Tech includes the necessary tool with each NPAS.

One component I wanted to completely swap out was the inner barrel. In place of the brass WE barrel, I installed a very lovely 500mm long 6.03mm stainless steel tight bore barrel from a new Japanese company, called "Angry Gun". I've used Prometheus and Mad Bull tight bores, and can say they have nothing on these new Angry Gun barrels. I firmly believe Angry Gun has raised the bar for precision inner barrels.

RA-Tech's well-regarded "White" buckings

WE is certainly not known for the quality of their barrel buckings. The first thing most WE owners do is swap out their bucking. Here, again, I used an RA-Tech “white” bucking in my C7. I've had rewarding results with these white buckings in each of my gas rifles, but RA-Tech recently introduced a new “blue” bucking, which is said to deliver even greater accuracy. I like to change buckings at the beginning of each airsoft season, so by next year I might be using the blue version instead.

One step I recommend, even in an AEG, is to wrap your bucking in Teflon tape before installing the barrel assembly back into the hop-up unit. A thin wrap of Teflon tape around the rubber bucking, past the point where it meets the barrel, and even a couple of centimeters down the length of the barrel, toward the muzzle, will help ensure a nice, tight fit between the barrel and the hop-up unit, and it'll promote a good seal between the bucking and the barrel, preventing gas leaks.

While I was reassembling the hop-up unit, I took the opportunity to install an SCS (Shredder Concave Spacer) in place of the stock WE hop-up nub. I find it a lot easier to regulate the amount of hop-up, using an SCS, and the accuracy seems more consistent too.

Hop-up adjustments in the WE M16 can be a royal pain in the butt!

Adjustments are made by turning a tiny allen screw located just above the chamber. WE does provide the proper size allen key, which they intended to be used by inserting the key through the ejection port. I, and other users, prefer instead to mount the allen key on the end of something like a thin wooden dowel, then making our adjustments by removing the bolt carrier assembly and accessing the allen screw through the back of the upper receiver. It's quite a bit easier than WE's suggested method.

As assembly of the interior components wrapped up, I turned my attention to the rifle's outward appearance. The biggest visible change was also the easiest to make...

Simply removing the detachable carrying handle exposed a short RIS rail running all along the top of the upper receiver. I used that rail to mount an Elcan C79 clone, which I bought from Airsoft Depot in Toronto. This $100 copy of the Canadian Army's standard issue optic sight is an absolute treat to use. In every way, it closely mimics the real item. It has proper 3.4X magnification, an easy to use needle shaped sighting post, sidebars to aid in rapid target acquisitions, realistic adjustment dials, and best of all – it's big, bright, and clear, with long eye relief. Everyone who's tried it, has loved it!

The only hindrance after mounting an Elcan is that it becomes a bit awkward to access the weapon's charging handle. The Canadian Forces resolved that by installing an extended/ambidextrous charging handle on all their C7A1s. The charging handle in use with the CF is a proprietary part, which I don't much care for anyway. I don't mind extended charging handles, but I have no need for one that's also ambidextrous.

I can't recall the brand name, but I found my extended handle on eBay.

Most other user controls on 1989/90 C7s were the same as an M16A3, including the magazine release, and the fire selector switch.

So, when I finished fitting all the bits and pieces together, I had a very nice C7A1 – a rifle that looks great, and which should serve me well down to Oklahoma.

So that's a review of how I turned an M16A3 gas blow back rifle into an accurate GBBR replica of Canada's C7A1 service rifle.

If anyone would like more info, just ask.
« Last Edit: January 16, 2015, 09:07:36 am by Rob Bye » Logged
Bane
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« Reply #1 on: August 03, 2012, 03:49:44 pm »

Did the C7s of the time period actually use RIS to mount the Elcan? I know rails existed but I don't know if they were used.
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« Reply #2 on: August 03, 2012, 04:08:52 pm »

Rails, yes. Not picatinny rails per se, as they weren't standardized until 1995, but they're pretty close.

Which 'raises' the question - how is the ELCAN sight mounted high enough to look over the front post? Is the riser an integral part of the sight or something different?

Anyway, very pretty article.
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« Reply #3 on: August 03, 2012, 05:38:39 pm »

Back then, Diemaco built C7A1s with a Weaver rail along the top. It wasn't a problem when they did switch to Picatinny rails , because anything that fits a Weaver can fit a Picatinny, but not visa versa.

Yes, we _can_ see the front sight post through our Elcans, but it's out of focus, so not at all distracting. We just learn to deal with that. The Elcan C79 is a single unit, with a fully integrated base.
« Last Edit: August 03, 2012, 11:10:49 pm by Rob Bye » Logged
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« Reply #4 on: August 03, 2012, 05:41:57 pm »

We traded in our C7 uppers for our new (railed) C7A1 uppers along with the new Elcans back in the fall of 1993. I recall the first annual rifle qualification scores with them were through the roof, so they had to re-jig the scoring system. Wink

Great as they are for shooting targets accurately at range - they do tend to create a bit of tunnel vision. However, luckily they come equipped with subtle rubber iron sights on top which makes engaging stuff close in actually possible.

If I had a beef about the weaver rail system and the Elcan - it's that you had to re-zero the weapon every time you took the sight off the rail when cleaning it.  Roll Eyes

Anyhow - fantastic post Rob!!
I'm sure I'll be bugging you for help when I convert my old closed bolt WE M16A3 over to an open bolt model.

Cheers!! Smiley
         Brian
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« Reply #5 on: August 03, 2012, 06:09:40 pm »

Man, you guys were ahead of the game (aside from still wearing OD, having no armor and using web gear); but you had rifles with rails and optics.  Tongue
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« Reply #6 on: August 03, 2012, 06:15:48 pm »

Man, you guys were ahead of the game...

The army maybe. I was in the navy - that was a completely different story.  Roll Eyes
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« Reply #7 on: August 03, 2012, 07:36:04 pm »

Man, you guys were ahead of the game (aside from still wearing OD, having no armor and using web gear); but you had rifles with rails and optics.  Tongue

Most of NATO still wore ODs or some equivalent at the time (the exceptions being the US, Britain and France). It was after the fall of the Berlin wall that things began to change. The Bundeswehr first trialed Flecktarn in 1976 but chose to sttick with OD because of this.
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« Reply #8 on: August 03, 2012, 08:11:43 pm »

Man, you guys were ahead of the game (aside from still wearing OD, having no armor and using web gear); but you had rifles with rails and optics.  Tongue

Most of NATO still wore ODs or some equivalent at the time (the exceptions being the US, Britain and France). It was after the fall of the Berlin wall that things began to change. The Bundeswehr first trialed Flecktarn in 1976 but chose to sttick with OD because of this.

I know, I was just messing the Canucks. You guys are no fun, I going to play with the commies...
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« Reply #9 on: August 03, 2012, 08:26:28 pm »

Very cool thread.

Where any of these in use at EW-V?  I believe the daytime temperature was perfect for GBBR's.  Did they hold up well in the dirt/dust?  Did you find yourselves breaking them down and cleaning them?  Is the GBBR C7 the Canadian Gold Standard rifle, or do you allow AEG's as well?  If you do split weapon types, is magazine commonality between squad-mates a big deal?  Were the realistic capacities ever an issue during any firefights?  Is there rifle mounted Night Vision, or do you also use helmet mounted like the US forces?  How does the helmet mounted night vision work with the Elcan (or replicas thereof)?

Way too much caffeine right now!  Grin
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« Reply #10 on: August 03, 2012, 09:09:48 pm »

Neat-o! I would love to see someone build a GBBR G3, but I haven't seen any of those anywhere (a couple quick google searches). I respect your effort, and admire your attention to detail!
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« Reply #11 on: August 03, 2012, 10:12:10 pm »

Hey Coop, to answer your questions:

Were any of these in use at EW-V?

No there were not - some good folks were kind enough to lend us some AEGs to keep us in business at EW5 (thank you again to those guys). Unfortunately, the laws for getting airsoft rifles back into Canada at that time prevented us from bringing down our own rifles. Those laws have since eased up a bit.


I believe the daytime temperature was perfect for GBBR's.  Did they hold up well in the dirt/dust?

As mentioned above, we didn't have any at Eastwind V, however I have one of these, but it's currently a closed bolt system. Anyhow, using it in similar conditions up here - it's not a problem. Just keep the ejection port closed and if you don't have a magazine loaded, be mindful of where you're setting your rifle down so nothing get's into the mag well, otherwise you're good to go. Having an NPAS negates a lot of the issues with temperature variation for a more consistent FPS.


Did you find yourselves breaking them down and cleaning them?

Regular maintenance is necessary, just ,like the real deal - but these rifles also break down like the real deal which makes them very quick and very easy to maintain. Even more so with the open bolt systems. 


Is the GBBR C7 the Canadian Gold Standard rifle or do you allow AEG's as well? 

Well, I think it's safe to say it's probably the rifle we want to make the gold standard. Cheesy,

However, one of the considerations we have to take into account are the issues we have in getting our Airsoft Rifles back into Canada. Those complications while not insurmountable, make the idea of picking up a cheap AEG in the States and leaving it with a Buddy down there or buying the rifle in the states and bringing it home in it's commercial packaging with the bill etc. - potentially cheaper and easier alternatives.

Anyhow, the WE M16A3 firing on Co2 is pretty snappy and the recoil isn't too far off from the real thing - just sayin. Wink


If you do split weapon types, is magazine commonality between squad-mates a big deal? 
I suppose it could be, but for the amount of shooting we typically do it's never posed a problem for us for far. I'm not sure whether it would be gaming the game to carry a mixed load so as to offset that potential problem. Ultimately though, I don't think that would be much of a problem unless we're ordered into a fight to the last round kinda situation. If we know that in advance, then I'm sure we could swap out with some secondaries and all run AEGs if we needed to.   


Were the realistic capacities ever an issue during any firefights?

Nope. I used to run 130, 190 round mid caps on an 11.1v LiPo shooting over iron sights and exclusively firing in bursts on auto so that I walk my stream of BB's onto my target so I was used to burning through a lot of rounds and quickly. However, when I transitioned to a GBBR it was sort of like going back to the real thing.

I'd count my rounds, and I'd only switch to full auto when I'm going into a built up area or a trench system - otherwise, she stays on repetition. With my Elcan, I'm able to see my individual BB's moving down range whereas over iron sights I can't (or at least not as easily).   


Is there rifle mounted Night Vision, or do you also use helmet mounted like the US forces? 

There was rifle mounted night vision, but not compatible with the Elcan. Specifically, we had the good 'ol PVS 2 Starlight Scope. For all I know it's still in service, but the last time I used one was in 1997.

Up until more recent times (Operations in Bosnia and Afghanistan) the CF was never awash in night vision devices of any kind. Those that we did have must have been pretty expensive as we'd see them once every blue moon to put batteries in them, test them and then put them back in a box never to be spoken of again for another year or so.

As for a helmet mount - we used the C1 (U.S. M1) Steel Pot helmet up until the late 1990's until it was replaced by our "new" Kevlar helmet. As such, there never were any helmet mounts for night vision. It was either hand held, stand alone goggles, devices fixed to a vehicle or a starlight scope on your rifle.


How does the helmet mounted night vision work with the Elcan (or replicas thereof)?

Well, again we had no helmet mounted night vision. Using any kind of night vision with an Elcan is probably an exercise in futility. What I will say for the Elcan though, and even the replicas is that the objective lens is fairly large so it takes in a lot of light which helps at night. On the real deal, there is some tritium on the tipp of the aiming post that is part of the reticle pattern. It lights up just enough to be seen, but not so bright it buggers your natural night vision.

Cheers!! Smiley
       Brian
« Last Edit: August 03, 2012, 10:17:29 pm by Fotheringham B.N. » Logged

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« Reply #12 on: August 03, 2012, 10:36:31 pm »

Several members of our team, here in Winnipeg, own GBBRs. As I don't even own an AEG, I'm certainly the most committed amongst our gas gunners. I'm probably also the most comfortable delving into their internals (I have a fair bit of experience building IPSC race guns).

Until recently, I think the KJWorks M4 (called C8A2 here) was the most popular choice on our team, but, with our growing commitments to Op East Wind, the WE M16A3 (C7A1) has probably taken over the lead now.

Our EW contingent, last year, had to use borrowed weapons, as Canadian laws made it extremely difficult for them to take airsoft rifles outside the country, then back in again. Canada's airsoft laws have since been relaxed, and we've also had more time to make preparations.

I've had no issues using my gas rifles here. Routine maintenance is about the same as it is for real steel. I break my rifle down after each of our weekend ops to give them a quick check-up and cleaning. So far, I've never needed to replace a broken part.

It's actually the magazines, anyway, which are likely to be a source of problems - in particular the fill valves. Improper lubrication and dirt entry can eventually take down a gas mag. As a safeguard, I'll bring plenty of spare valves to EW for servicing our magazines.

We don't require our 6 CGB team members to use any particular model of rifle. Sure, the East Wind contingent uses C7s and C8s, but the rest can use whatever they like, with a preference for those types which can accommodate standard NATO M4/16 mags. We want to, theoretically, be able to share mags, but that need seldom comes along. Even though we now have several WE C7s, mine is the only one using the "open bolt" system. All the others are "closed bolt", so we use slightly different mags. Before next March, most of the other rifles (and their magazines) will be converted to open bolt - then we'll be able to more easily share mags.

Temperature is, of course, an issue for all gas guns. Below 5℃, propane won't cycle the weapon properly. At that point, we'll have to switch to CO2 magazines, which should take us down to the freezing point, and slightly below. It should be pointed out that AEGs have their own problems dealing with the cold, so I don't feel we'll be at any disadvantage there.

As for night vision, I know Al has a Canadian NV scope designed to fit the older FN C1 rifle. We're hoping to get a look at it when he visits us next month, and we'll see what we need to do to mount it on one of our C7s. Beyond that one scope, I don't know of any other night vision options for us. Canada apparently never fielded any sort of helmet mounted system during the "Trudeau years".
« Last Edit: August 03, 2012, 10:46:05 pm by Rob Bye » Logged
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« Reply #13 on: August 03, 2012, 11:25:16 pm »

To add to this, Cam, our German of Canadian heritage, had a GBBR G36 and that thing was sweet! Besides the last battle it only ever got fired at night and had no trouble.
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« Reply #14 on: August 15, 2012, 11:39:01 am »

I recommend dental floss mod(cleaner and easier to install while making sure air seal is best) instead of teflon mod when tightening air seal on hop-up bucking.
« Last Edit: August 15, 2012, 11:41:39 am by ComradeHX » Logged

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