How to remove blasting caps from shell casings:
Before decorating or applying etchant resist, you will need to punch out the spent blasting caps. You can drill though the ends using titanium bits, but punching them out is usually faster and easier. The caps have an inner piece so you are really drilling through a couple layers and you can end up with jagged holes and broken bits. Ammo reloaders have their own specialized tools for this step (see sample press here) but unless you are going into mass production, you won’t need this!!
Set up your work space on a bench or sturdy place not affected by hammering. I use a slab of wood, cushioned by a piece of non-skid shelf liner on my workbench. This keeps the block from damaging my counter.
Place punch (nail punch, awl or other) into the empty casing. There is one (sometimes two in larger calibers) divot inside the end of the casing which you can "feel" with the punch.
(By the way, nails, brass screws, even cheap awls are NOT good for repeated used. They bend, which can damage the brass shell, and even break themselves - see blue punch above.)
MidwayUSA and other gun supply places carry decapping bases and hand punches, which may make this step easier.)
Soon, your punch will poke through, pushing the cap pieces out and into the hole in the riveting block.
IF that doesn't work you need stronger measures. Wrap the casing end with a piece of leather and gently grip with pliers or vise grip. If it's really stuck, wrap the brass with several layers of masking tape and try again.
NEW: Found a better way!! You can buy special narrow punches from gun suppliers that are designed to punch these! Check at www.midwayusa.com and search for "decapping punches".
Be sure to check the gauge of your shells so punch is correct size. They also have corresponding "bases". Using this punch and base is MUCH easier.
Please to the next step, Plug Those Holes.
Scrub brass with green scrubby and Barkeepers Friend or Penny Brite (if you can find it) or other powdered cleansers to remove any oil. Especially if using rubber stamps or toner transfers. Water should sheet off, not bead up. Refrain from touching with fingers which adds body oils. Or soak in your jeweler's pickle solution. Other things work as well, but oils hinder the etching.