I welded with NR205.  It was a root pass wire for use on pipeline welding.  It was a single pass electrode.  It had to be covered with a NR207 Hot pass and fill passes.  It could bridge a 1/4 inch root opening.  It was part of the Lincoln LN-23P welding system.  You had to go to Lincoln school in order to buy the system or the wire.  It was made for very fast XC pipeline welding.  When used as a system it also had Charpy products better than E-7018 deposits.

Joe Kane