Cutting Die From a Shotgun Cartridge/Shell

I was recently given a collection of spent shotgun cartridges (US: shells) by a member of a local gun club, as I wanted to explore the metal ferrels’ (US: heads’) possibilities for crafting purposes. The first thing I decided to make was a leather keyring (US: key chain) with an inset 12-bore (US: 12-gauge) ferrel, as a present for the donor. The only problem was that I don’t have a 20.5mm diameter punch or die to cut a circle for the ferrel, and my efforts to cut such a small circle neatly with a knife weren’t very successful. So I experimented and found a way to use a ferrel as a die to make a perfectly circular hole of exactly the right size.

At some point I’ll produce an ‘Ible showing how to make the keyring in the photos. This one only describes how to use a ferrel to cut a circular hole in leather, whether it’s to take another ferrel or because you need a hole for another reason. It may also work for materials such as cork and thin wood veneer but I haven’t tried yet. Shotgun cartridges come in various sizes, with 12-bore the largest that is commonly found. If you ask nicely at your local shooting club you will probably be able to get a range of sizes, right down to 36-bore which will make a hole that’s only about 11.8mm in diameter.

Supplies

A spent (ie fired) shotgun cartridge

An electric iron

Slip-joint pliers

Ordinary pliers

A wine cork (real cork, not synthetic)

A sharp knife

Double sided sticky tape

Safety glasses

Two house bricks or blocks of wood

A hammer

A drill and 9mm / ⅜" bit

A nail punch, or a nail with the tip sawn off

Scrap wood

A cork mat, HDPE or nylon chopping board, or a newspaper

Scrap leather to practise on, up to 1mm thick (2½ oz)

Step 1: Selecting the Cartridges

If you want to embellish leather goods with shotgun cartridge ferrels, you’ll need some extra ones to use as the cutting dies. I was able to use the same ferrel twice before it became too distorted, but seeing as you can usually obtain them for free I’d suggest getting hold of enough to be able to use a new one for each hole. Ask around and someone you know probably knows someone who shoots game, vermin or clay pigeons, at least in country areas. Otherwise, google to find if there's a local gun club and drop them an email to beg for a handful of assorted spent cartridges. If all else fails, you can find them for sale on eBay and elsewhere.

Having got hold of some, sort through them to find the ones with ferrels you want to use for embellishment and the less attractive ones that can become dies. Rusty ones are fine as long as the open edge of the ferrel - the part that fits over the plastic or waxed paper case (US: Hull) - isn’t too rusty. Modern ferrels are mostly brass- or nickel-plated steel, not solid brass, which is good because steel ones are stronger and sharper. Test with a magnet if you are unsure.

Ferrels vary considerably in length, and the shorter ones are less likely to buckle under pressure when used as a die. So reject the taller ones.

I have only used cartridges with plastic cases, and they can easily be separated from the metal ferrels with heat by watching for when they start to soften - see next step. Avoid any with traditional paper/card cases unless you are prepared to carry out some experiments to discover how their ferrels can be removed.

Step 2: Removing the Ferrels

Start by preparing the spent cartridges for their new purpose. Safety first: slosh them around in a bowl of water for a minute or two to remove any gunpowder residue that might be in there. It’s unlikely anything explosive will remain in a cartridge that’s been fired, but better safe than sorry because you are going to be heating them next. Stand them up to drain for a while, ferrel uppermost.

While they’re drying, prepare the jaws of the slip joint pliers you’re going to use to hold the ferrels. They need to be covered with something that will prevent them from scratching the metal. Cut small pieces from a wine cork and then stick them onto the jaws with double-sided tape. Adjust the slip joint of the pliers to the right position to enable them to hold a ferrel and pick one up to test the force you need to apply to get a firm grip without distorting the circular shape. You need to pick them up by the cylindrical part, not the larger diameter rim.

When the cartridges are mainly dry – a few drops of water won’t matter – get out your iron and, without turning it on yet, set the temperature control to the cotton setting. Tip out any water in it and turn off the steam. Then prop it between two blocks of wood or bricks with the soleplate uppermost and as horizontal as possible. Plug it in and switch it on at the wall. Give it a couple of minutes to heat up then put on your safety glasses in case there’s any steam spitting as a result of water left in a cartridge.

Place a cartridge, ferrel down, in the centre of the soleplate. Watch it closely and after perhaps 2-3 minutes you will see the plastic case start to soften and wilt, no longer standing vertically. This means that it’s ready to be pulled away from the ferrel. Grip the ferrel - using no more force than is necessary – with the slip joint pliers held horizontally in your left (or non-dominant) hand and lift it off the iron. Quickly grab the top of the plastic case using the ordinary pliers held in your other hand and twist while pulling gently to remove it. Then put the metal ferrel down on one wooden block or brick to cool and the case on the other one.

If you find the cartridge won’t pull apart easily, just pop it back on the iron to heat for a bit longer. You’ll also need to put it back on the iron if there’s a lot of gluey or plasticky residue left in the ferrel – they appear to be stuck on with a hot-melt glue that is clear when melted but turns white as it cools. So put the ferrel back on the heat if there’s still white stuff, or coloured casing plastic, visible when it has cooled for a couple of minutes. Watch it carefully as it heats up again and pull out the glue/plastic (using the two pairs of pliers again) the minute it turns clear - if you leave it longer it will be too liquid to come out in one piece, but if it’s still white then it will be stuck to the metal. You need to get all the glue and plastic out of the ferrels that will be used as cutters.

Repeat with any other cartridges you are planning to use. Once you have got the hang of this process you can place a bunch of them on the iron at the same time (assuming you are making a bunch of leather goods) and quickly separate the ferrels from them one by one as you see the cases start to lose their rigidity.

Step 3: Removing the Primers

The small circular thing in the centre of a ferrel is the primer which ignites the powder in the cartridge when it's struck. The primer protrudes through the ferrel, sticking up in the centre of the underside by about 7-8mm. In shorter ferrels the primer will reach, or nearly reach, the open end. These short ones make the most successful dies because their circular edges can take a greater pressure without bending and buckling when they're used to cut through leather. But the primer will need to be removed or it will just rest on the surface of the leather and stop the edge cutting through.

To remove the primer, take a piece of scrap wood and drill a hole in it that's a little bigger than the copper ring around the outside of the primer. 9mm (⅜") is a suitable size. Drill it all the way through the wood, or else to a depth that's a little shorter than the primer (so that you can grab hold of the primer to remove it from the hole ready to do the next ferrel).

Place the ferrel right side down (ie open edge up) on the wood with the primer right over the hole. Hit the primer with a hammer and nail punch (or a nail with the tip cut off) to knock it out. A couple of light taps should do it.

You'll be left with a spiky ring of pressed metal sticking up inside the ferrel, that previously held the primer in place. It should stop well below the circular edge though, so it won't get in the way when you use the ferrel as a die.

Step 4: Cutting Holes in Leather

The ferrel needs to be supported internally to prevent it from collapsing when it's used to cut a piece of leather. A slice from a wine cork does the job. Cut a slice that's thinner than the internal height of the ferrel by the thickness of the leather or a tiny bit more. In other words, if the inside of the ferrel is 7mm tall and you are going to cut a 1mm thick peice of leather, then the cork slice should be a maximum of 6mm thick. Cut or punch a hole in the centre that's just big enough to go over the metal spikes where the primer was.

Fit the cork slice into the ferrel, pushing it fully home. A standard wine cork is a fairly good fit for a 12-bore ferrel, but you may need to trim a little off outside to get it in, and you definitely will if you're using a 20-bore or something even smaller. The cork needs to go in quite tightly to support the thin metal edge that will do the cutting.

That done, place the leather (right side up) on an HDPE chopping board, a cork mat or a similar surface that will absorb some of the shock - a folded up newspaper will do. Then put the die/ferrel where you want the hole, sharp edge downwards. Place a small piece of wood on top and, holding everything in place with one hand, strike the wood several times with a hammer to cut a hole. Hit both in the centre of the ferrel and all the way round the edge. After a few hits the ferrel should be stuck in the leather and it will be safe to pick them up together and turn them over to see which parts of the circumference haven’t yet cut through and need a few more bashes with the hammer.

Pry the circle of leather out of the ferrel with a knife. It’s possible to re-use the same one as a die maybe once or twice, but after that it’s likely to be too distorted and/or blunt.

I have only tried this with fairly thin leather, up to 1mm thick (2½ oz). I think it will work on a skin that's a bit thicker, I'd be interested to hear the results in the comments below if anyone gives it a go. Similarly, I haven't tried using an arbor press or a vice to apply the cutting force instead of whacking the ferrel with a hammer, but I don't see why it wouldn't work just as well.