Thursday, July 27, 2017

Mk12 Mod 1 build - KAC Free Float Rifle RAS

The parts are starting to trickle in and the latest to arrive is the KAC Free Float Rifle RAS.  At $514.49 CAD, it was probably one of the dumbest expenditures I've made in my efforts to build a clone.  But, I've already started to walk down this plank, so no point in grumbling about it now.

As with all the KAC products I've encountered so far, when you open the packaging, you get the feeling they mean business.  Simple cardboard box, no flashy markings.  Inside, the RAS was sealed in a simple plastic bag and the instructions folded neatly underneath.

The fit and finish is top notch, nothing wobbled, no loose or rattling parts.  It was surprisingly lighter than I expected.  I didn't weigh it, but I had it in my mind that the old style cheese graters would be heavy.  Of course, if you want to start saving grams here and there, you can always go with an M-lok hand guard with no rails (until you install them), and likely for less than half the price of this unit, but then it wouldn't be clone correct.  I know, so OCD.

So, an updated picture of the collection of parts I've amassed for this Mk12 Mod 1 build.  I was planning on waiting until all the parts arrived before assembly, but I decided screw it, may as well start slapping together what I could.  

As you can see, the barrel is completely wrong.  It's not a bad barrel, in fact, this particular Colt HBAR produced sub MOA groups, but I didn't like the look of the build it was sitting in (PWS build with keymod handguard).  As you can see from the picture, the channels were cut into the barrel for the front sight taper pins.  I'm not sure, but I don't think these would be cut in the proper 18" Douglas barrels.  Also, to the Mk12 expert (not me), the heavy HBAR profile is different from the Mk12 barrel profile.

Off comes the barrel nut.

I probably should be referring to the instructions when typing this all out, but it's not handy so you'll have to bear with my made up names for the parts.  Spin off the end cap and the barrel nut should just drop out.

It's got two pins that you will need later.

Slip the cap down the barrel first and have it sit against the upper.

Then spin on the barrel nut.

The flat side should be towards the muzzle.

You'll have to time the holes so one of them lines up the hole in the upper for the gas tube.

Installing the gas tube and gas block is pretty straight forward.

Next, I installed the Allen Engineering brake and collar.

The collar has a set screw in it, and for my build, it's really just there for looks.  First, we can't have suppressors for which it is meant to align, and second, my barrel profile isn't correct, so I really have no idea where it's supposed to sit on the barrel.

I set it just under an inch away from the gas block for now.  I could always move it if necessary.

The brake came with a standard crush washer.

Then basically install the brake like any other muzzle device.  With the crush washer, I cranked it 1/8 circle turn at a time, backing off, then cranking forward until the brake was timed properly, with the narrower bridge on top.  The best way to do this is using a cresent wrench with painter's tape wrapped around the the surface of the wrench to prevent scratching the brake.....but I didn't bother with the tape.

Looking at the side profile, it didn't look right to me.  Compared to pictures of other Mk12 builds, the gap between the collar and the brake was far too much so I relocated it closer to the brake.

Spin the thread protector back on and this part is done.

It doesn't look horrendous, but the barrel is clearly two inches too long to be considered a proper clone.

Next, take those pins and drop them in the 3 o'clock and 9 o'clock positions.

Slip the hand guard over the barrel and fasten the end cap onto the hand guard threads.  I just hand tightened, but I hear there are tools out there to crank it down more.  

Once it was all together, it felt sturdy with no wiggle whatsoever.  Other free float hand guards I've used in the past were all fastened on with some sort of screws or clamp to the barrel nut.  Well, this design has seen plenty of experience so I have no worries about the design.

I threw my Patrol on there, which looks slightly off, but at least the rings are somewhat correct, lol!  Also just grabbed a bipod adapter and one of my Champion pivot bipods.  I'll spring for the correct mount and a Harris one day, but I'm not in a hurry for those parts.

Again, I borrowed the lower from my Mk18 clone just to get an idea of what the thing will look like.  Now all that's left is the stripped lower, A1 stock, and KAC front sight.

I really need to find a cheaper hobby. 

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