Hey guys, I have a mutt build of an MCX that is LVAW-ish. 6.75” 300BLK Virtus barrel, legacy receiver, F01 gas valve. Currently suppressed with an EA Vox.

Here’s my issue: I shoot 110gr or 125gr supers exclusively. This rifle is unpleasant at best - extremely gassy even in the (-) gas valve position. Some of this is undoubtedly the can.

If this was a DI gun, a BRT tube would be an easy fix. I’m not well versed on the MCX. What are my options to tune here?

Would a cut down 16” barrel offer a smaller gas port? Or am going to need to look at a flow through type suppressor?

Attached File

Looking at this https://sheffieldtactical.com/f/sig-mcx-gas-plug-port-sizes maybe the C01?

By the way, I used to have a 16" legacy blackout barrel cut disc to 8.25" and it was awesome.

I ended up just going with a factory 9" in the long run though.

EDIT: You could have a gunsmith weld the hole closed and redrill the desired size. I have heard of people doing that before.

Have you considered looking for a newer style flow thru style can?  There are quite a few companies making them now and it would mostly mitigate the problem.

I retired the old style can on mine and am very pleaded with the result.

What did you replace it with?

First time I've seen that info compiled, good stuff.

I'm wondering if anyone knows....
Are all the gas plugs interchangeable, at least within caliber?

I was hoping as the platform matured they would make different/multiposition gas plugs available for stuff just like this.  This is the biggest single item I liked better about my 516, the three position gas plug with a real suppressor setting was really nice.
I understand why you may not want that on a military rifle, but for the civ market, it seems like it should be easy enough to offer.

So, it's funny you ask that.

Mototech, who makes some really cool gun part (mostly for the SCAR) just announced that they are working on some kind of gas regulator for the MCX.

I think there's another company working on something too.

Unless you want to try just throwing in another factory valve, I'd probably just hold off and see what comes to market.

Great info, thank you!

I am going to end up picking up a CAT ODB for this rifle, but since I plan on shooting exclusively suppressed supers, a gas regulator that allows me to tune for function with only supers supressed would be ideal. I'll hold off and keep and eye out.