I've just brought a new delta ring for my ics m4 so that my old magpul hand guard would fit on, I've looked at it but I'm really unsure on how to remove the current one and put on this new one!
Not on an ICS, There is no barrel nut with teeth. You just twist the delta ring untill the cutouts match up with the two wings on the barrel and should pop off, then unscrew the barrel nut whilst pulling the barrel forward.