Removing the thread ring that connects and ISC RAS rail to an M4 upper receiver

[Figjam]

Hi guys, Im having a nightmare with this. I have a buyer for the rail, but he's going to need the thread connector that the rail screws onto and connects the rail to the upper receiver. This is not like a delta ring or anything else I've had hands on. It looks like it needs just a 3-4 degree turn clockwise and it should just slide off, but it's not shifting. Is there a trick to this?
I'm uploading a video showing the problem, although today youtube is being a git, so will add that when its done.

[Figjam]

Re: Removing the thread ring that connects and ISC RAS rail to an M4 upper receiver

A vid showing my problem

[julesbloke]

That just unscrews. It's probably on there really tight (it holds the barrel in place so needs to be) and/or thread locked so it doesn't come loose.

You can either use an armorers wrench that is crescent shaped and has raised bits that fit the holes or buy a rubber boa type wrench and see if that gets enough grip!

[Figjam]

Re: Removing the thread ring that connects and ISC RAS rail to an M4 upper receiver

wow, it is insanely tight then, the plastic upper receiver was really creaking like it was going to break. Any tips for what to brace the receiver in? I have a rubber boa thing.

[julesbloke]

Re: Removing the thread ring that connects and ISC RAS rail to an M4 upper receiver

Mine was on a metal receiver, so probably a bit more stable. I would think clamping it along the rail on the upper using something like a work bench or something would hold it in place.

Here's a (bad) pic of a disassembled one. It needs more than twisting a few degrees. You keep undoing it and pulling the outer barrel forward as you go. Both pieces will come off at the same time and then you slip the ring off the outer barrel. You might actually find it easier to reattach the RIS and tighten it on then twist that. Should give you enough torque to loosen the ring/barrel nut. It may also be threadlocked (glued) on. Try pouring some boiling water on it to heat it up and loosen the glue before you twist - be careful obviously

[Johnno]

Re: Removing the thread ring that connects and ISC RAS rail to an M4 upper receiver

Mine just screws on/off but you do need a Peg Spanner to get it moving, an Armourer's Wrench will do it but the spacing of the holes doesn't quite match :-(
Sometimes nipping it up a tad tighter breaks the bond and will make it easier to undo..

[Figjam]

Re: Removing the thread ring that connects and ISC RAS rail to an M4 upper receiver

Thanks guys. All makes sense and Ill give it a whirl. Picture is alo very helpful, gives me a clue as to what its all about.

Just to check, it it clockwise or anti? from looking at it from the barrel end?

[Johnno]

Re: Removing the thread ring that connects and ISC RAS rail to an M4 upper receiver

Looking from Muzzle down to Receiver..anti CW..

[Figjam]

Re: Removing the thread ring that connects and ISC RAS rail to an M4 upper receiver

Thanks for all the advice, did boiling water and improvised an armourers wrench and its come off sweetly. Job Done!