Ok. I have a 3" 2nd stage connected to an AC-74 Airframe Coupler connected to a 3" 1st Stage. The ID of the coupler is 2.851 inches. Obviously, the 2nd Stage (with fairing and parachute and Jolly Logic Chute Release and altimeter) has to separate from the 1st Stage so that the 2nd Stage engine can kick off, but does anyone sell a 29mm centering ring that will go inside this coupler? Do I have to sand down the standard 29mm centering ring to fit inside the coupler -- which will just float there when the two stages separate? It seems like I am trying to do a pretty standard thing here, so what am I missing?