A bit of advice when you go to buy your new AK barrel. A 16″ AKM or AK47 does not need a gas port larger than 3mm to run correctly. If it does you have other issues. Yes I have seen a few factory rifles that were larger but the recoil was noticeable. These were milled rifles too. Several of the new barrels that have come in for assembly lately were in the neighborhood of 3.5mm. Yes their recoil was noticeable. So if you are buying a virgin Barrel for a project get one with a 3mm port. However if you have the ability to assemble it yourself or are going to send it to us. Just get one without the port and you or I can drill it to the correct size. Also we have the resource to have your plain barrel nitrided or FNC coated if you wish. Happy Shooting!!