The mat underneath the cast powder coated bullets was one of those silicon grilling mats for the BBQ grill that I cut in half and then clipped the corners to keep them from turning up. I do the spraying on another tray that is covered with alum foil so it takes the overspray of powder and I have to clip the ground clip to a metal ground to get the gun sprayed powder to have a charged on the bullets. I then use a large hemostats to move them from the powder application tray to the bake tray. Also, it is as mentioned the alloy needs to be of the correct hardness for the velocity your planning to shoot them at, the coating is not going to protect the bullet from being driven faster than they should be just because they have a coating. Most times I apply any gas checks before coating due to many of my cast are shot as cast. They will be run through the lube a sizer just to apply the check.