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Hey Sam,
So I’ve had my 556 with the 10.5” barrel for almost a decade now. I first shot it with an AAC M4-2000 suppressor about 4 years back. I had a similar experience as you described with the rifle being over gassed but I didn’t experience any failures of any kind. The rifle would just eject casings 40+ feet. For reference the M4-2000 suppressor is really bad with back pressure.

I was not aware and still don’t believe these guns have a suppressor setting but I have not actually used a pin gauge to measure the two factory gas ports to confirm what I believe.

The way I solved this problem was, while researching I found a guy on an old forum that would modify the gas valves by essentially mirroring the location of the two gas ports, but when adding the new ones he just used smaller holes.

He set me up with a “degassed” setting and a suppressor setting. The results really surprised the heck out of me. “Degassed” setting has the ejection at approximately 10’ to the 2 o’clock position, I would describe it as perfect. The suppressed setting is the same, I would call it perfect.

The guy who did the work for me was great to work with however I’m a stickler for this kind of machine work. It appears he did the work with a basic end mill or a drill press so the machine work itself leaves me wanting to do it again but I want to have my friend who is a machinist recreate it.

I have a second gas valve laying around. So what I plan to do on the near future is have my friend use a pin gauge to measure the port sizes in the valve I had worked on, then he will locate the new port holes and essentially recreate the part that I know works perfectly.

If it turns out to be a success using my buddy, I will get back on here and get the two of you in contact. I’m sure for a small few he would help you out.

Feel free to reach out and send me an email and we can discuss it further.
[email protected]
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