Another Compact Cartridge Slam Fire

This is a miniature version of the Big Boy 50 Cal BMG variant. I call it the Elk Model because my son is a big game hunter. He is going out west to hunt elk this season and has encouraged me to make up a bunch of these using spent 300 Win Mag Cartridges. Some folks will tell you these are not long enough to make a usable ember. But they work very well.

Shown in the image at the bottom are a couple of carry containers for O-ring and tinder  fashioned from spent brass casings.

Granted, these small fire pistons require a bit more savvy and practice to get embers every time, simply because the small size makes it a little harder to compress quickly and snatch the piston rod back out in order to keep the ember alive. But I have a technique that works with even my old arthritic and nerve-numbed hands. If I can do it, I think pretty much anyone can learn it. It may take a couple of dozen times to get the technique down, but you will see how well it works when I post my video clip demonstrating the technique. I will add it here (AT&T service has downgraded terribly in recent times to uploading takes forever).

Meanwhile, a brief description should help in learning this technique. I am right-handed, so I hold the brass casing in my upper left hand with the projectile end facing my right hand, on top of my middle finger. I hold it in place and control it with my thumb and index finger of that same hand. With the primer end of the casing braced firmly against the fleshy part of the heel of that palm, I use the right hand thumb and index finger to insert the lightly lubed o-ring end of the piston rod into the open end of the casing. I like to push the piston all the way in slowly one time to make sure the inside of the cylinder is properly lubricated and giving good push-back. I then withdraw the piston to where the o-ring is just inside the cylinder opening. Using the fleshy part of the heel of my right-hand palm– diametrically opposed to the one the brass casing is braced against–I slam the piston rod into the the brass casing part.

This technique allows sufficient speed and force to be applied to get ignition. Then, by quickly grasping the end of the piston rod with my right-hand thumb and top two fingers, it can be quickly withdrawn in order to allow the ember  to breathe and keep  ember burning. I usually blow it gently. Sometimes it doesn’t even look like the tinder catches until you blow it and see the red ember. Obviously a video would be a better way to illustrate this technique, but it is really is less complicated to do than it was to write how to do it. Whew!

Now by the Numbers

Getting the piston rod solidly in and out quickly is the key to success with any fire piston. It is slightly more difficult to do with compact fire pistons, but this technique works well

  1. Make sure the cylinder inside is clean, free of old tinder and lubricant. Wrap a piece of paper towel longer than the cylinder around the cleaning rod and scour the inside of the cylinder thoroughly. The inside can be washed with a weak dilution of detergent water, but it must be allowed to dry  completely before using. It is usually not necessary to use anything more than a dry paper towel.
  2. Wipe the piston rod down and make sure the rod, o-ring, and tinder pocket on the business end are free of debris and and lube.
  3. Apply fresh lube very lightly to the o-ring only. You want enough to enable easy sliding and a complete seal without leaving excess or residue which will inhibit the tinder from lighting. The tinder must be completely dry and free of lube to ignite. It is best to develop a habit of using a middle finger to apply lube, saving the index finger and thumb to place the tinder–thereby eliminating any chance of contaminating the tinder.
  4. With clean, lube-free fingers, pick a piece of tinder just large enough to fill the tinder pocket. Don’t pack it tightly but make sure it does not hang out the sides. It is okay and desirable for it to remain slightly fluffed.Note: You may find it helpful to reverse steps 3 and 4 if it helps you keep the tinder free of lube.
  5. Start the rod into the cylinder opening and push just past the inside of the cylinder taking care to make sure it enters straight. Gently push the rod all the way in one time to lube the inside of the cylinder, then withdraw it to where it is just inside the cylinder. You can feel where the inside cylinder begins–just even with the point where the neck of the cartridge gets bigger. The o-ring should be just inside this point.
  6. Hold the primer end of the cartridge solidly against one hand–either the heel or the fleshy part of the palm just below the index finger. You will want to be able to firmly grasp the cartridge with a thumb and first two fingers, while providing a solid platform to push against.
  7. Ready the rod for a firm and quick push using the opposite hand by placing the end of the rod against the fleshy part of the palm just below the thumb. Once you get a solid push into the cylinder, it will ignite–but it will immediately extinguish itself because of Oxygen starvation–unless you immediately snatch it back out again to let it breath.
  8. To remove the rod quickly enough to keep an ember burning after ignition, you will need to grasp it firmly with the thumb and fingers of that hand. It may take a few times to get this technique down. Slam it in with the pad of the palm below the thumb, fingers up out of the way, and then wrap your fingers down around the piston rod end and snatch it right back out–both maneuvers in one fluid motion. Getting the piston rod solidly in and out quickly is the key to success with any fire piston. It is slightly more difficult to do with compact fire pistons, but this technique works well for me and others I have taught to use it. As with anything, practice makes perfect. If you cannot get a live ember within a few good solid slams, check to see if the tinder has turned black. If it is black, you are not removing it quickly enough. If it is not black, you are either not getting a good slam, or the tinder may be contaminated and should be replace with a fresh piece.
  9. When the tinder both ignites within and is removed quickly enough–you will see it glowing as you  blow very gently to keep it burning.
  10. Transfer the live ember to a larger piece of tinder or to a tinder bundle and kindle to flames. I don’t smoke, but it can also be used to light a cigarette or pipe as was commonly done during the first part of the 19th century. (It is often told that the inventor of the Diesel engine observed this being done by one of his professors, using a novelty fire piston brought back from a jaunt among primitive tribes in the jungles of Malaysia–thereby inspiring the method Diesel eventually used for igniting the fuel in his now famous invention.)

There are also some nuances to making these things. I invite you to try to make you own. You can learn to make them work if you are patient and willing to spend the time messing with them. It took  a while for me to figure out a consistent procedure. It is more art than craft; but they are made very much like my bigger models. Since few people seem interested in doing this, I am offering these on eBay for less than the cost of my materials and time.

I have never posted any eBay link before, so I don’t even know it it will work. If not you can search for my eBay name MILITARYOPTICS and pick it out of the few items I have. I may not offer very many or these or for very long–but if you want one, you can contact me and I’ll list one there.


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