Finished converting my M74 ak to 556 yesterday. Riveted everything up and pressed in the barrel last night. No other mods except mag swap and barrel swap. Bolt and extractor work fine with 556. Passed Go/No Go.

Need pics!..... sounds like a cool project...

Let see if i can

Pay attention to ejector contact on the rim. Some ejectors are not long enough and the case rim can actually pass to the side of the ejector. It can even peen the ejector.

Easiest way to remedy this is to remove the extractor and file the small flat shelf on it where it contacts the bolt. This allows the extractor to extend further into the rim. Test fit until you get a tight fit on the 5.56 rim, but not so tight that a live round can't be rotated by hand when inserted.

This pushes the 5.56 case closer to the ejector as well, ensuring full ejector engagement.

You may also find that without this mod, the 5.45 bolt can potentially drop a round when held upside down. After the mod, it will not.

My 5.56 74 has been a great shooter and totally reliable, but I did have to perform the above mod for the NDS-2 and it was NOT one of the earlier ones that had short cut ejectors.

Oddly enough it cycled perfectly fine before the mod but I could see on spent cases that the ejector wasn't extending far enough out into the rim.