I have used .223 and 30-06 cases for charge wells, but as Fred said they are conductive. For ematches with the plastic covers on them just tape them in place so they dont slip and insert in the powder charge, the plastic cover will keep them from possibly shorting on the chargewell walls or bottom. I also use a lot of drilled aluminum rod as charge wells, again they are conductive, but a 3' section of aluminum rod is relatively cheap and in lots of diameters. Center drilling the rod is actually pretty easy using a bit mounted in a vise and the rod mounted in the drill chuck (like lathe drilling).