Friday, February 22, 2013

Punch Caps from Shell Casings

How to remove blasting caps from shell casings:

See previous post for list of tools and materials.

Blasting caps in bullets are just what they sound like - a small cap (or cup shaped piece) which contains gunpowder which explodes when gun is fired, sending the bullet on its destructive way.

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!!

Once fired, the cap pieces remain in the bullet. Three shown here - left one is inverted, lower right one has small three-legged piece removed. (I have no idea how this works - you can find lots more info on the interweb if you need it.) That said, I do save all these pieces. They look a bit like tiny bezels or may find their way into use as inclusions in resin or as tiny endcaps someday.

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.
Sent punch into this small hole and center over a riveting block hole, larger than the end cap. Rap the punch a couple times with the mallet or small hammer. At first the casing may slide when struck - carefully hold it upright with your non-dominant hand until the cap begins to extrude.

(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.)

Knowing how hard to hit is something you will learn. Too timid and nothing happens, too hard and your punch will get stuck - which may happen anyway. Usually 3-4 good raps will pop out the cap, however some bullet brands are "tougher" than others and seem more difficult to work with.
As the cap will begin to come out it becomes easier to center over the hole in the anvil. (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 you didn't force the punch too deep, the casing should pull straight off. You may need to twist it a bit - use a rubber jar opened/gripper to grab the casing.

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.
If you are careful, your brass will remain un-marred.
However, it is easy to scratch and damage the brass. Rough edges can be filed smooth and maybe incorporated into the design.
Now that there is a hole in each end, the next step is to PLUG those holes (to keep the etchant from going inside the casings).

NEW: Found a better way!! You can buy special narrow punches from gun suppliers that are designed to punch these! Check at 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.

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