It's been a while since I've worked on a NHM but I think you remove the forward FSB retaining pin and you should be able to remove the detent.Hello, on a NHM91 there is a fixed plunger pin preventing the muzzle nut from being removed. What is the best way to remove or un-stick the plunger pin? force it in? or pull it out because it's made longer and won't go in?