Welcome and congratulations on your first and what I can guarantee won’t be your last MG purchase. I started this addiction back in 2004. You will find that you will buy suppressors to keep you busy between buying MG’s. That being said,I don’t own an AC556, but I considered buying one back when they were about 6-7 thousand dollars. The reason I decided against it, is the fact that I own a Mini 14. I really do not like shooting it all that much. It is loud, and when shot, sounded clunky like an old beat up pickup Truck. Never mind the gas blast to the face. I did a few things that made it more tolerable shoot. The first was to install a Wolff extra power recoil spring and a recoil buffer. I don’t think you can go wrong when you stop the metal to metal impact. I put the gun in a Hogue overmold stock. This helped with clunky sound. Lastly I customized my gas block to cut down on the gas flow. This seemed to cut down on the gas blast to the face due to lower chamber pressure on ejection. Even after all that I still don’t shoot it much. Mainly my 10” SBR AR. Now I would not mess with the gas system on a transferable MG, but the spring,buffer , and stock you may consider. Enjoy your new bullet hose. My 2cents FWIW.