Can anyone tell me what this part is?  On my Bushmaster 25th Anniv. carbine, I am trying to remove the barrel.  I have successfully removed the one-piece free-floating handguard and its jam ring and the gas tube.  At this point I thought I would just be removing the barrel nut with an armorers wrench, BUT there is another little ring around the barrel sitting in front of the barrel nut that I believe is keeping the barrel nut from moving.  It is a solid ring about 1 1/4" diam. and 1/2 " wide with two holes on its outside 180 degrees apart as though meant for a spanner wrench, possibly even a tele-stock wrench.  I have tried to remove this little ring to no avail.  I'm not even sure if it's really separate from the barrel nut or one piece.  This ring and the barrel nut are on there really tight.  Any info would be appreciated.  I can send anyone a nice picture of it with their email address.... don't have a way to host the pic on a URL.  My email address is:  [email protected]

It sounds to me to be the nut for a free float tube . There should be two pins on your armorers wrench just for the reemoval of this nut .

Thanks for the reply.  The nut for the free float tube is about 2" in diameter and rides around the barrel nut and has four slots in it for a spanner wrench.  The ring in questions sits in front of the barrel nut on the barrel and is only about 1 1/4 " in diameter.  It has two holes on the outside of its perimeter.  It may be a lock ring to keep the barrel nut from coming loose or it may be part of the barrel nut, I can't tell which, but I'm not putting any more torque on it until I find out more.  This must be a new part that Bushmaster has started using.  

I know exactly whay you are talking about as I had the same problem.  That ring is part of the nut.  It really does not have a function. Call Larry at YHM and he will send you the new style barrel nut.  You will have to clamp a monkey wrench very tight on the threads and it will damage them but it is the only way to remove it.  Once you have the monkey wrench secure on the threads you just loosen it like you normally would.   You can then use the new barrel nut from YHM to re install it.    I have the tool that YHM makes specifically to install/unistall the new type nut and it made everthing a lot easier once I got the old type nut off.  The new style does not have the ring in front of the nut.

Post a pic if you can the ring with the 2 holes may be a snap ring and they make a set of pliers to remove this also a heavy duty barrel wrench has the 3 pins on the opposite side that will alow removal of the free float tube,not sure if I would put a monkey wrench to any thing until you try using the right tools.Oh and an upper receiver vice block is worh its weight in gold when removing/installing barrels,free float tubes and tourqing the nut back on.

Trust me there is no snap ring.  It is all one piece.  Larry at YHM said "do whatever you have to to get it off and I will mail you the new style barrel nut that does not have the extension".

Thanks to mlm1219.  I'm glad I have finally found someone that knows what I'm talking about.  And thanks to model927 for the reply also.  If it is all one piece why can't I just take it off with my armorers wrench like I would if it didn't have the ring extension?  The torque should be the same shouldn't it?  Maybe one could use a spanner tool on the ring at the same time as using the armorers wrench on the barrel nut.    I don't know how to put a picture on a URL and you can't host from your hard drive on this board, so the only way I can get anyone a pic is if they give me their email address so I can just send it to them.  Thanks guys.  

The armorers tool will not fit it.  I tried. When I spoke to Larry he said they used to have a tool that would fit the holes on the outside of the small ring (2 at 180 degrees).  I then asked him well what should I do.  He replied "whatever it takes to get it off" and don't worry about damaging the barrel nut b/c I will send you a new one in the mail.  I then clamped a monkey wrench as tight as I could onto the threaded portion of the nut and spun it right off.

My armorers wrench fits over the ring and into the holes like it does on all barrel nuts, but I can't budge it; that's why I thought maybe the ring was a separate lock nut. It must be torqued on at over 100 ftlbs.  I'm glad to know it is only one piece anyway.  I will keep working on it.  I guess a call to Bushmaster when they open tomorrow wouldn't hurt.  Thanks again.