WK-180C/WS-MCR: Why the Mid Length Piston?

The topic of replacing the factory 180C/MCR piston with a mid-length piston has been coming up over and over again.  Rather than re-typing the information, I have decided to place it here.

For ease I am going to say that for the duration of this article, I am going to collectively call the WK180C and WS-MCR, the Canadian 180 pattern rifle. Both are loosely based of the AR180B.

The 180 pattern rifle uses a carbine length gas system to push a piston that in turn moves the carrier backwards enough that a cam causes the bolt to rotate and unlock.  The residual pressure then pushes the bolt and carrier back ejecting the round and picking another round up.  The bolt and carrier move back at about 4 to 5 meters per second.

Now the original AR180B platform used a rifle length piston system.  The rifle length port provides only 14% of the gas pressure as the carbine port.  Yet it works.  It cycles, it has a very long life span.

So when I heard about 180 rifles breaking (pistons and bolt lugs being the main culprits) I had to question why.  The answer was obvious: there is too much pressure.

It is akin to using a sledgehammer to put finishing nails into your wall to hang pictures... it can be done, but the chance of too much force being applied and creating damage, is very real.

Now the AR180B was designed in America.  It is not speculation to say that they have milder weather then us.  Perhaps the carbine length was picked to ensure cycling if frost formed on the gun?  Maybe it was because it is easier to snap a long piston?  Maybe it was as simple and sinister as cost cutting... I didn't know.

I didn't want to risk potential reliability in cold weather so I examined the possibility of making the Canadian 180 a mid-length piston.  The mid length has 5000PSI less pressure at the port.

So I built it: the Mid length piston.  And that's all that I needed to build; the original gas block still worked and there were lots of mid-length ported barrels out there.  

With a mid length piston, the rifle shot softer and put less wear on parts.

If you are using your Canadian 180 pattern rifle to casually target shoot, this upgrade isn't for you.  The warranty on broken carbine pistons is great.  A broken gun can be brought back up to operation in 2 weeks or less with the friendly and helpful staff at Kodiak.

But if you want this to be a rifle that you use hard, competition or survival, you are best off upgrading.

Visit Specterarms.ca to pick up a piston today.