This has probably come up before but I had purchased a RR one piece rear sight nut (drum) to go from my standard A2 rear sights to NM. The rear sight base came from Brownells and had the two piece drum. it turns out that the RR nut is a finer thread than the NM base??! Measuring the click value the Brownells base is .002 per click which is about 1/3 minute. Where in the world did that come from? Who would ever choose 1/3 minute sights? Just curios. TIA
Tom