[metroplex]

What's the size of your stock/current gas jet orifice? Someone else on Reddit was complaining that their SCARburetor wasn't working consistently either.

My SCARburetor is still backordered, but I do have a 3-select regulator and that should definitely work for you. There are 3 settings: stock, 20% reduction, 40% reduction. I verified the hole sizes. Everything else about it is basically the same as the factory regulator. The factory regulator's 2nd setting only reduces gas flow by 4% by comparison.

KNS has a DiSCARder that was back in stock and I placed an order for one as well.

 

[metroplex]

Stock jets for the 16" SCAR 17 are 1.5mm.

4% reduction for the suppressed position of the factory regulator sounds low to me. How did you figure that? Also, the suppressed position has more venting to reduce the gas pressure too.

Side note: It's interesting that my location flag changed to Mexico since I'm on vacation here now. I didn't realize it would do that.

I was asking the OP the actual size of his gas jets and not the book values.

The stock suppressed setting has an opening 4% smaller. The other holes are all the same size on the Moto 3 select as well, except for the main hole. On the 3 select its 20% smaller then 40% smaller (I measured the hole that sits basically over the gas port).

If that doesn't make sense, then imagine your stock regulator. Add an additional setting. They are incrementally smaller by 20% but everything else is the same.
Eddie has said on the 3 select you get the full stock sizing, then 20% reduction, and then another 20% reduction.

The FN flash suppressing regulator actually has the same size holes for both settings for some reason. It must depend on the other mini holes for venting, but the stock OEM regulator has a 4% smaller main hole.

And yes I see the other holes inside the regulator as well and like i said they're the same size on the 3 select and FN flash suppressing version.

My scarburetor has been on BO for almost 3 months so I can't see how it works, but I do have the 3 select and I think it's far less complex

 

[metroplex]

So you never measured them yourself even with 2 of Mototech's 3-select regulators, a SCARBuretor, and at least 1 OEM regulator?

From my own notes:
Mototech 3-select regulator: 0.108", 0.085", and 0.065" vent holes. Basically full setting, 20% reduced setting, 40% reduced setting.
OEM regulator has 0.108” and 0.104” vent holes (4% reduction)
FN OEM Low-flash F141290020 has both holes at 0.105” (0% reduction).

 

[metroplex]

I know you said you’re using the stock gasjet but what is the measurement. It wouldn’t hurt to double check it as a baseline.

the newer FN flash suppressed regulators don’t seem to have a difference in gas reduction between normal and suppressed (same size).

 

[metroplex]

How many rounds have you shot through it without removing the gas screw? I put about 2000 through my 16S and it was totally seized in there. I ended up having to drill it out. Kind of a PITA to be honest. If you have drill bits/pin gauges it would help measuring.

 

[metroplex]

Are there any other holes around the Scarburetor that is inserted into the gas tube? The OEM/3-select have multiple smaller holes not directly over the gas screw. My guess is that while the main port over the gas screw is going to be the restriction, excess gas trying to leave will flow around the regulator as well and exit out the front that way as well. So the gas port over the screw isn't the only restriction if that makes any sense.

I'm still thinking the 3-select regulator is the ultimate for the SCAR as it is simple (OEM style design)

 

[metroplex]

Might try to get a few of the PMM jets as they are hex head and good quality stainless. The way it went for me was the OEM jet was a "real joy" to remove being a particular size flat head and soft metal. I got one out of one 17S but my other 17S was such a pain that I had to send it in to PMM for removal, was embarrassed about that as I'm pretty good with tools. When I got my 20S that was the very first thing I did during the initial cleaning.

I had to remove the gas screw from my Belgian 16S (I'm the original owner and put about 2000 rd through over the years) and it wasn't fun. The PMM tool was garbage as it stripped and then stripped the stock gas screw. I tried heating, PB blaster, etc... and nothing worked. I drilled to extract it and luckily it came out in chunks. It was a harrowing experience and more importantly the barrel wasn't damaged. This is why I recommend to every new SCAR owner I see to immediately consider removing their stock gas screw and apply some anti-seize if they ever want to change gas jets in the future. The PMM/aftermarket screws are definitely better but you can also buy the stainless set screws and drill the jet holes yourself. The PMM screws I bought came in wrong sizes, luckily one matched what I needed and the other was small enough that I could drill it open to what I needed.

 

[metroplex]

I ordered my KNS DiSCARder last week and received it today. There are 14 settings (0-13).

The part that sticks into the gas port measured 0.436" and the part that sticks into the gas port groove is 0.105"

The way it works is that it has a big opening that sits over the gas port of the barrel. As gas flows up through this opening, it flows into the piston chamber and goes into an inner chamber on the regulator (as the rest of the gas pushes at the piston). This inner chamber of the regulator leads to a triangular cut-out on the outer part of the regulator (looks like an inner sleeve is pressed in), and there are at least 3 tiny holes at this cut-out. So in the "0" position, this port is completely exposed and presumably ejects all excess gas out the 1'oclock position (when facing the rear of the rifle).

The knob spins both ways, you can go from 0 to 13 directly and vice-versa. At position 13, that triangular port is completely blocked. At position 12, just a tiny part of the port is open. Etc...

To me, this is still the same venting design as the OEM FN, OEM FN Flash Suppressing, and Mototech 3-select regulator: excess gas vents outside the piston chamber. On the KNS, it ejects out the 1 o clock position and anywhere else that is "leaky" like the sides of the regulator. On the OEM FN and Mototech 3-select, it can go out the front or the sides of the regulator.

I do not have my SCARburetor yet so I can't comment on its operation/flow.

 

[metroplex]

FWIW the jets that come with the KNS seem to be made of better SS. It's got the wheat finish like H900 heat treated 17-4 you see for suppressor mounts (e.g. Q Cherry Bomb, Q Plan B, etc).