I am posting this here in the hopes that other Colt owners and gurus can chime in if they can, not just 901 owners.
I have an AR901. I removed the rail to send over to ADCO for barrel reprofiling. I had sent this upper to ADCO a few weeks ago in the hopes that they could remove the barrel the same way they have done other 901s. Unfortunately, they were not able to remove the barrel. They said that this is a different barrel nut that they have not seen before. They returned the upper back to me at their cost.
I contacted Colt to find out anything that I could. They do not have a part number, nor do they sell a barrel nut wrench specific for the AR901; I knew this was probably going to be the case but I tried anyways. They also would not allow me to send them the upper to have them remove the barrel for me, so that I may then send to ADCO for reprofiling and then back to Colt for reassembly. They were also not willing to disclose much information about the pin on the underside of the barrel extension area.
I am trying to find out if I can have a custom barrel nut wrench made. But before I do that, I wanted to understand a little bit more about the purpose of the silver pin underneath the barrel nut, as seen in the pictures below.
Have any of you seen this before?
What is the purpose of this pin?
Is the barrel nut pinned in place? (this would suck)
Do the other 901s also have this pin?
Do other Colt rifles have pins similar to this?
Thanks for any information you can provide.