I have the cod connected to the butt plate with some velcro on the sides. I also added velcro ALL along the insides of both pieces. I also have velcro strategically placed along my flight suit as well. that presses into the cod/butt armor when pressed in. The final piece would be aluminum studs that screw the cod into the butt piece. I can send you pics if it would help.
The belts lay on top of everything, helping to hold it in place.....