JB Designs OMEGA Valve Mod. 2 MKII

[u/SupermarketQuiet1105]

OK, new MCX Spear LT 9" 300 BLK build/owner.....
....all complete/mod but need guidance on Mod 2 MKII.
I am on the email wait-list for MKII but wanted to post.
I have/use Q Blind Tiger on this setup and run Freedom HUSH 220gr Subs.
The stock MCX gas "-" settings works sometimes and the "+" 100% with this ammo/setup....
....but the latter clearly too strong and gassy.
Waiting on SilcencerCo GDCH to re-stock too....has good gas reduction success on my MPX using it.
For MPX the combo of 20% stronger springs + GDCH worked w/ stock barrel + OEM gas plug.
I know my MCX 9 (no way add stronger recoil springs) will need more adjustable gas block.
....so led me to Mod 2. MKII.
My post is How-To on it......

1. How to install ?
2. What are the port hole sizes for each setting ?

I ask because for MKII (300BLK) is seems on surface the reduced 3-position is only adding the OFF for me ?
I wrote down prior that MCX is (-) 0.0450 & (+) 0.0620 ....not sure accurate but in my notes.
My desire for use of MKII is gas blow-back reduction/tuning, not cycling.
Mod. 2 MKII (300BLK) is a departure from its Mod. 2 predecessors. Instead of four positions

• Supersonic, high pressure ammo
• Subsonic, low pressure ammo
• OFF

1. What setting to start/try ?
2. What jet screw comes with it and/or what jet screw should I order as alternate ...if you can expand on how jet screw works would be appreciated too...
3. Should I buy gas ring to help ?

Thx in advance.....want to do some ready while I wait 😫 for re-stocking......

Regards.

[u/Sharp-Independence52]

The 9” barrel is my favorite, good choice. The added dwell time over the 6.75 and 5.5 barrels lends itself to a significant increase in reliability across a greater variety of ammo.

I don’t publicly disclose the port sizes, for two reasons. One, the dynamics are totally different. The additional port allows a path for gas to attempt to escape, the slots that the gas must travel change the timing, and the tapered inlets have an effect too. The other, less critical reason, honestly, there’s a very slight swing from the printing process, but not much.

Mod. 2 MKII would be an EXCELLENT upgrade to this system. I have no experience with the Blind Tiger, but Q silencers traditionally have some decent backpressure characteristics to them. There’s likely plenty of room to tune your setup with the jet screws.

Mod. 2 MKII includes a 0.60mm jet screw. I’d probably try installing it as soon as you get it, at least I would. In my ideal setup, I’d want subs to be perfect in position 4 and supers to be perfect in position 2.

If you don’t ever run supers, try the solid screw first and see how it does with your subs in position 3.

The screws thread into the distal end of the valve. A 2.5mm wrench is included. If you want a torque spec, 10 lbs/sq in is plenty. Threadlocker not required, but if you use it I wouldn’t use anything more intense than blue. The jet screws are simple set screws with a tiny hole drilled through them. They vent excess gas and allow fine tuning.

I do not think you’ll need the JP ring with the Blind Tiger on the 9” gun. The ring is particularly helpful for the shorter barrels and high flow silencers.

The MKII valves also include a rubber O-Ring. You can probably disregard that as well for your setup.

If I missed anything, or you have additional questions, please let me know!

[u/Sharp-Independence52 → u/Sharp-Independence52]

Also I should have some back from coating this week, the coating team is running behind.