A true DI wk180c, will it work?

[diegocn]

I am fiddling with installing a new barrel on my wk180c today. I had to file down the gas block to get it line up with the gas port on new barrel. All this work makes me wonder if we could make a DI wk180c work.

The inspiration comes from French MAS 44. See Ian's video on MAS 44, 10:50 starts to explain the gas system.
https://youtu.be/gCjzyzYVWIc

Basicaly, MAS 44 has a gas tube blowing straight into a simple hole in the bolt carrier. Unlike AR15, gas does not go to the internal piston. It literally just blows the bolt carrier back.

This makes me wonder, on wk180, the bolt carrier already has a pretty beafy area where the piston impinge on. I guess it wouldn't be hard to cut a hole into that area, and install an adjustable AR gas block and gas tube to make everything work?

Anyone see any problem with this thought? I am not familiar with MAS 44 or French rifles in general. Is there a reason the MAS 44 design isn't wider spread?

 

[OkayShooter]

If it wasn't designed for it, probably wouldn't be best to. Main thing I see. The bolt doesn't have gas rings on it, so it won't really seal, and blow gas all over the place.

 

[Hornychief]

What barrel are you using? Id be pretty hesitant with how the upper is a lot more open closer to shooter and ends up gassing you.

 

[Suther]

If it wasn't designed for it, probably wouldn't be best to. Main thing I see. The bolt doesn't have gas rings on it, so it won't really seal, and blow gas all over the place.

The bolt isn't involved in a true DI system like it is with the AR. If you look at the specifics, an AR is actually closer to a piston system that uses the bolt and carrier as the piston. True DI just slams hot gases into the front of the bolt or carrier.

 

[Blastattack]

If it wasn't designed for it, probably wouldn't be best to. Main thing I see. The bolt doesn't have gas rings on it, so it won't really seal, and blow gas all over the place.

The Ljungman doesn't have a gas seal, just a bolt protrusion and a cup. Wouldn't be too hard to add those to a 180.

The bolt isn't involved in a true DI system like it is with the AR. If you look at the specifics, an AR is actually closer to a piston system that uses the bolt and carrier as the piston. True DI just slams hot gases into the front of the bolt or carrier.

Absolutely true. The AR15 really isn't a direct impingement gun at all, but a very ingenious inline piston system.

 

[Travis Bickle]

It could work.
The ar15 design sends almost all the gas into the carrier behind the bolt itself to start the carrier moving rearward first.
The carrier moves rearward until the cam unlocks bolt in the barrel extension/chamber and take the bolt with it to continue the cycle.
The carrier has the two gas vent holes in it to release the excess pressure of the system as well. So most of the nastiness of the system gets focused into the carrier not the actual chamber or places that really need to be clean to prevent stoppages. It's a common misconception and flawed misunderstanding of the mechanical design leading to the "####s where it eats" stupidity you see a lot of people parroting.

That's why you see the heavy heavy carbon fouling behind the actual bolt behind the gas rings on the tail of the bolt and the very rear of the carrier the bolt seats into.

Theres no reason a gas system into the wk180c wouldn't work.
Some of the problems you will encounter though is:
Regulating the least amount of gas to hit the bolt so it cycles reliable without over gassing or under gassing it. Would recommend an adjustable gas block.
Now actually having a rifle that truly does "#### where it eats" as the carbon and nastiness of the gas system will empty in front of the bolt and right into the chamber area.
One way you can get around this is to bore into the bolt carrier the diameter of the gas tube. And then bore a vent hole or holes perpendicular into the carrier to allow excess pressure to vent. Thats assuming your tube projects into the upper receiver enough.
One way to get around this would be use a mid length gas system barrel and use a rifle length gas tube. You could then custom cut the gas tube to the length you desire.

You may then also face issues with the gas tube being in the right spot to line up with the piston hole to pass into the upper receiver.
If you need to you could machine a sleeve to press into the old piston hole to ensure the gas tube is held good and tight in place as well.
But that still being said this system would still result in a lot of fouling into the chamber, magazine, bolt face area every time you fired it.
The adjustable gas block will allow you to fine tune it.
That being said I would also open up the gas port of your barrel prior to installation to ensure you have enough wiggle room in case your adjustable block is maxed and you still need more pressure.
I hope any of that made sense to you! This is just from my head without having an ar15 or a 180 action at hand to study.

 

[Suther]

I have to ask WHY you'd want to do this? A major reason DI never became widespread is the fact it's dirtier than other systems. If the Wk180c already has a functional piston system, why muck with it?

 

[diegocn]

Now actually having a rifle that truly does "#### where it eats" as the carbon and nastiness of the gas system will empty in front of the bolt and right into the chamber area.
One way you can get around this is to bore into the bolt carrier the diameter of the gas tube. And then bore a vent hole or holes perpendicular into the carrier to allow excess pressure to vent. Thats assuming your tube projects into the upper receiver enough.
One way to get around this would be use a mid length gas system barrel and use a rifle length gas tube. You could then custom cut the gas tube to the length you desire.

You may then also face issues with the gas tube being in the right spot to line up with the piston hole to pass into the upper receiver.
If you need to you could machine a sleeve to press into the old piston hole to ensure the gas tube is held good and tight in place as well.
But that still being said this system would still result in a lot of fouling into the chamber, magazine, bolt face area every time you fired it.
The adjustable gas block will allow you to fine tune it.
That being said I would also open up the gas port of your barrel prior to installation to ensure you have enough wiggle room in case your adjustable block is maxed and you still need more pressure.
I hope any of that made sense to you! This is just from my head without having an ar15 or a 180 action at hand to study.

Thank you for the insight! I was thinking ways to reduce the fouling but it seems vent holes are the best bet. Rifles like MAS 44 or AG42B has a open top and vent directly out. But the WK180C enclosed upper receiver will become a problem.

Gas port alignment is another issue. The WK180C uses a nylon/polymer bushing to guide the piston into upper. This probably makes things easier should it need modification. I think a tapered gas tube and a chamfered bore on the bolt could manage it.

I have to ask WHY you'd want to do this? A major reason DI never became widespread is the fact it's dirtier than other systems. If the Wk180c already has a functional piston system, why muck with it?

I am just toying with the idea as my hand is pretty full just doing the barrel swap. One reason is I think the gas piston op-rod is a weak part in the WK180C design. If the gas block is not aligned properly with the gas piston hole on the upper, the piston rod tend to break. Misalignment can happen due to gas block improperly secured. This actually happened on my very early serial wk180c (but KD took care of it like a champ).
The other reason is to reduce the reliance on proprietary parts and use more standard AR parts.

 

[Ohno]

I can think of a couple of advantages of a true DI system. One would be weight savings and the other would be less mass moving back and forth.

 

[dieseldog]

You have to remember too making it DI you are not only introducing dirty gases depending on propellant but also raising the temperatures of all parts involved and possibly creating additional issues from the temps that where never of a concern in the original AR 18, 180, and B design. ——Dieseldog!

 

[lawn gnome]

Diegocn,,,what you are talking about is a Jard 48.
DI system to bolt carrier face.

Check out the company website and look at the Jard 48 manual to see a very good drawing of exactly what you are trying to recreate. An AR180 turned into a DI system.

Strangely enough, Jard 48s are a bit hard to find in Canada.