gas port size question

[PA_Allen]

I have a Thunderbeast 30BA on the way in a few months, and I am thinking of adding an adjustable gas block to my 16" mid-length gas upper. What is the consensus on the optimum port size for suppressed and unsuppressed for a 16 mid Grendel? (I found an old thread where Bill Alexander recommended 0.078" port size for unsuppressed 16" mid-length gas.)
I have looked at the screw adjustable blocks like the SLR or Syrac, but the idea of a two or three position switch or plate like the MicroMoa Govnah or Noveske Switchblock is very appealing. Anyone have any experience with the Govnah or N. Switchblock on a Grendel?
Thanks,
PA_Allen

[Adam Lilja]

I would think if you have an adj block you would want the biggest size hole you can for the biggest range in PSI.

[cory]

We were talking about this today on another Thread, it was posted that the hole should be around .120 to .125, 1/8". That will let it cycle with mid weight and light weight. I'm going to be doing this on Saturday to mine as I'm having the cycle issue too. Hopefully doing that size hole it will cycle the 220gr too.

I will say the SLR is nice and the detent is a great idea but not enough testing yet. My JP is nice but the screw gets stuck and is harder than hell to get loose. Maybe I'm suppose to take it out more frequently but it has been set fine for so long I hadn't tried to move it. Then went to 95gr and tried to tighten it, no go there...bought some Kroil to try and break it loose, as suggested by other forum members...

That was for the 300 blackout with a pistol length gas system, completely different animal

[LRRPF52]

Yes, .078" unsuppressed. Whatever setting you find with an adjustable that will produce the results you're looking for suppressed.

There will be more dwell time, so you'll have to turn it down into the happy window, but it might cycle fine with no adjustments from the start, just on the hard side.

You could choose to tame it with an MGI RRB as well, or heavier buffer.

[PA_Allen]

To clarify, I'm more interested in the optimum port diameter for an adjustable gas block for suppressed and unsuppressed for 16" MGL grendell, not the barrel port size. The port size in my barrel is fixed at it's current size (unknown until I pull off the current gas block). Adjustable blocks like the MicroMoa Govnah allow you to pick two or three fixed port sizes by the use of a sliding plate. They list preferred sizes for various 5.56 and .300 Blackout configurations, but nothing for the Grendel. So I was wondering, if you could pick, what would be the optimum gas block port sizes for the Grendel.
Best,
PA_Allen

[LRRPF52]

Ok. I looked at their site and I see what you are asking for. If it were me, I would get this one:

“Milspec” plate – .078” – unsuppressed position / .055” – suppressed position

If that doesn't work out for some reason, then you could go custom on the suppressed position, but .078" will work for your unsuppressed use for sure. It should run well with the 123gr suppressed on the .055" setting. Cool system really.

[PA_Allen]

Ok. I looked at their site and I see what you are asking for. If it were me, I would get this one:


If that doesn't work out for some reason, then you could go custom on the suppressed position, but .078" will work for your unsuppressed use for sure. It should run well with the 123gr suppressed on the .055" setting. Cool system really.

Thanks. That's what I was thinking as well. Having a simple, two setting block for a lightweight carbine is very appealing for easily running with and without the suppressor.
I might give it a try......
Thanks,
PA