Make Your Own Snap Caps for a Rifle





Introduction: Make Your Own Snap Caps for a Rifle

About: I miss the days when magazines like Popular Mechanics had all sorts of DIY projects for making and repairing just about everything. I am enjoying posting things I have learned and done since I got my first ...

A snap cap is a "dummy" bullet that allows a person to fire an unloaded rifle without damaging the firing pin. Firing a rifle without live bullets allows a person to practice a solid stance, careful aim, controlled breathing, and a gentle squeeze of the trigger. These skills are essential to good marksmanship and a snap cap makes it possible to practice them without the expense of firing live ammunition.

The bullet on the right is an 8 x 57mm Mauser rifle round. The bullet on the left is a snap cap I made from a spent shell casing, an 8 - 32 brass screw, a portion of a 5/16 inch bolt, an 8 - 32 steel nut, and enough hot glue to fill the brass shell casing.

If you search "DIY snap cap" in a search engine, you find a post about making a snap cap for an odd sized caliber by pushing out the spent primer cap from a brass casing and using epoxy glue to adhere a section of a common pencil eraser. I am using original military surplus ammunition made in 1947. It uses the European style primer cap, which does not push out like the US style cap.

Step 1: My Rifle

This is a photo of my rifle. It is a Yugoslav Mauser. It was made on captured German machinery and is nearly identical to a K-98, except for the national markings. It was made in the years following World War II when most countries in Europe thought there might be another war soon. They produced extra rifles to be kept in warehouses so they would be ready. That war did not come and semi-automatic rifles came into production, rendering the bolt action Mauser obsolete. This rifle is in beautiful, factory new condition after almost 60 years in a warehouse. It was never issued.

When I first wanted a snap cap, I could not find any for this rifle's caliber. In recent months I have found some on the Internet.

Step 2: Drill Through the Primer Cap

Notice the indentation from the firing pin on this spent casing. Drill a hole into the indentation. Make the hole just a bit larger than an 8 - 32 screw. Use a countersink bit to remove burrs on the outside of the casing. (If you use a vise, be careful not to crush or distort the casing. The very end is quite rigid and will not easily crush or distort. Grasp it in the vise. I wrapped a piece of bicycle inner tube around the casing to protect it from gouges and scratches from the vise jaws.)

Step 3: Machine a Standard Nut

The photo shows an 8 - 32 steel nut using an 8 - 32 screw as a mandrel to turn the nut by holding the spinning drill near to a grinding wheel. Not only do you want to remove the corners, but you want to reduce the diameter of the nut until it will just pass through the opening in the shell casing's neck.

I have one of those magnetic tools with a stiff spring shank that allows one to reach into corners and retrieve small steel parts. I placed the machined nut on the end of it, pushed the nut inside the casing, and used the magnetic tool to hold the nut over the primer hole so I could start the brass screw into the nut. It was not difficult at all. Pull the nut against the inside of the shell casing with the screw once the nut is started and turn it almost finger tight. A little looseness is fine. The looseness aids in aligning the screw parallel to a center line running down the shell casing, when the time comes.

Step 4: Add a "bullet"

The finished snap cap will not properly cycle through the rifle's chamber when the bolt is operated unless there is something resembling a bullet in the neck of the casing. If you do your own reloading, you can press a bullet into the neck of the shell casing. For anyone without a die and a reloading press, you can make a satisfactory bullet from a piece of rod. I cut the head from a standard 5/16 inch bolt. Then I chucked it in my drill and held it against a grinding wheel, as with the nut in Step Three. Vibration frequently loosened the grip of the chuck's jaws and I had to stop to align the bolt and tighten the jaws.

Step 5: Fill With Hot Glue

I adjusted the alignment of the 8 - 32 brass screw so it was pointing straight toward the center of the hole in the casing's neck. Then I began to fill the casing with hot glue. When it was full to about the neck I inserted my facsimile bullet. I tried to make certain some hot glue covered the threaded portion inside the casing. I was concerned that the hot glue might have cooled as it was flowing down the inside of the casing, so I lightly played over the outside of the casing with a propane torch. Be careful to try to keep the brass screw in the primer hole straight during all of this. Also watch out that the facsimile bullet does not sink down inside the casing. The casing will be almost too hot to touch with your fingers. Have a couple of pliers nearby.

When the hot glue has cooled completely, use a screwdriver and turn the brass screw out of the casing. This breaks the threads loose from the hot glue. You will probably need this later. Put the screw back into the nut.

The plan--

The nut inside the casing is nearly as large in diameter as the casing. It acts like a plunger when the firing pin strikes the end of the brass screw. The nut pushes against the solidified hot glue inside the casing. The solidified hot glue cannot move because the shell casing is tapered, especially at the neck of the casing. And, the solidified hot glue has some elasticity similar to hard rubber. Commercial snap caps have a spring to absorb the strike of the firing pin. This snap cap has the elasticity of the solidified hot glue.

Step 6: Make the End of the Screw Neat

Saw the head from the brass screw. Then file what is left of the screw so it is exactly flush with the end of the shell casing. Any extra remainder on the screw will decrease the headspace in your rifle's chamber and the bolt will not close. The rifle will not fire.

Here you can see the bicycle inner tube protecting the shell casing from the vise jaws.

Step 7: Success

In this photo the bolt has picked the snap cap up from the magazine, locked it to the bolt, and is about to push it smoothly into the chamber. This snap cap works quite well.

Step 8: When the Brass Screw Wears Too Much

In time the indentation in the brass screw will have a larger and larger dimple. If the dimple grows to be too large, it will be as if you are firing the rifle without a shell in the chamber and you could damage the firing pin.

The indentation you see in the snap cap (left bullet) is the result of about ten releases of the firing pin. After ten more the indentation was still about the same. I believe the solidified hot glue is doing its job absorbing the shock of the firing pin as it should.

You already know you can turn the screw in the nut's threads. You can back it out, as long as you have a slot for a screwdriver. Place a thin cutting wheel in a Dremel tool and make a shallow slot. It is no problem if you cut into a little of the casing's end. Use the smallest screwdriver that works to back the brass screw out a turn or two. File the impromptu screwdriver slot and the dimple out of the end of the screw. Make it flush with the end of the casing so there is no headspace problem, and you are ready to get more use out of your snap cap. If you completely use up the brass screw, insert a new screw and repeat the process in Step Six. You will be ready to go again.

This snap cap works well with a tapered casing, especially one with a shoulder. Some further thinking would likely be necessary for a bullet with no taper, like a .45 Colt ACP.

Also, it is often recommended that snap caps be painted some bright color so no one confuses them with live ammunition, and, worse yet, vice versa.



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    63 Discussions

    I just thought of a good way to keep your vise jaws from damaging your casing, which would be to make some protective jaw covers out of magnets, sheet metal and a couple of giant erasers. You should try it some time, I'm sure it would work.

    Interesting, actually it was a recalcitrant Yugo Mauser that got me into making my snap caps. I was bound and determined to be a single shot and I wanted at least 5 dummy round to work on its feeding problems. Converted a batch of old Rumanian once fired cases and solve his problem. Turns out the strippers I was sold as being correct for the rifle weren't. Got some strippers that work and I'm ready for the military bolt gun matches this season. Enjoy the day,


    well, i dont wanna start an argument but you are trying to move a lot of mass/weight that the firing pin usually does not do. yes, it usually does hit metal but it hits thin metal and moves about [i am guessing] 0.2 grams of metal [just the dimple]. you now have it hitting and trying to move a solid slab of metal that weights about 20 grams? just guessing that is about 100 times heavier or 10,000 percent more weight. might be better to modify your idea a little. in my opinion most snap caps dont simulate primer strikes very accurately either. live primers decelerate the firing pin with deformation. primers do not store the striking energy and return it to the firing pin. if they did, i dont see how there could be a dimple in the primer after firing. LOL anyway, some sort of compromised alternative is needed for "dry firing" and snap caps are it so far. let me ponder on this topic for a while and i'll see if i can think of another way no-one else ever did.

    um not the best thing for your firing pin using a filed brass bolt filed flat. Most snap cap has a spring in them so they dont damage the fire pin.

    7 replies

    I think there is some springy force absorbtion in the hot glue that is between the nut I mentioned and the neck of the casing. I did buy a couple of commercial snap caps from A Zoom for this rifle. Whatever springs are inside them are very stiff. I cannot detect any deflection on the plug where the firing pin strikes, no matter how hard I push with a tool. I know the brass is softer than the firing pin. If you have some information you can point me to, I would be interested in it. Thanks.

    Well the firing pin on most rifles is a very hard and violation acting. The snap cap spring is very stiff. But this spring will slow down the firing pin down. Glue is not a spring and when your firing pin hit the brass screw it doesn't have any where to release this energy. You could actually damage or snap your firing pin when using a spent round or a brass screw. When you damage your firing pin, depending on your bolt. It hard to replace the firing pin in your bolt. That why I always use a snap cap with a spring. It has the spring to release the energy from the firing pin.

    I compared an A-Zoom commercially made snap cap for this rifle with my home version. The commercial snap cap makes a very metalic ping when I release the firing pin. When I release the firing pin against my homebrew snap cap there is a quiet little dull thud. I had a friend with lots of gun experience fire both in succession to see what he thought. He found the metallic ping from the commercial snap cap disturbing, but liked the quiet thud of my homebrew snap cap. Unless we are both fooled, the homebrew snap cap seemed to be much more gentle on the firing pin.

    I would be more concerned with the steel firing pin hitting a steel bolt repeatedly, resulting in the firing pin peening or mushrooming. Have you noticed either?

    I am not quite certain what you are asking. The steel firing pin does not hit the steel bolt. The firing pin hits a brass screw cushioned with hot glue, and there are air space in the hot glue to absorb the shock.

    I wouldn't use your snap cap because like I said before using a used fire case or a brass bolt could damage my firing pin. When I have use a snap cap for my rifle there is a very loud ping sound. That loud ping sound is the spring inside doing it work. Like I said before the spring slows down the energy from the firing pin spring so it doesn't damage the firing pin. Even when you have a live round in your rifle the firing pin make a loud ping sound.

    Even though I've dry-fired my VZ-24 Mauser about a thousand times with nothing in the chamber, my firing pin has been just fine, thus I don't see a practical need for dummy rounds other than to practice loading and testing the action of a weapon with them. These firing pins are pieces of hot-forged steel, and I think Phil's concept of using softer metal as the strike target is a sound idea. It won't do any damage to the firing pin as long as the softer brass absorbs the impact, though I do question whether or not the brass would eventually deform to the point that it would necessitate replacement?

    Hi again, from Alan in La Grange, KY. Good article here. My Dad was a Gunners Mate in the US Navy (1944) and had quite a wealth of knowledge regarding armaments and munitions. One of the first lessons he taught me as a kid was to never "dry fire" a rifle or pistol for fear of damaging the firing pin, especially in older guns as yours. My question . . . is dry firing a modern rifle made in the last few years (such as an AR-15 - .223 cal) as much a concern ? I have several recently manufactured high powered rifles and there is little mention in the owners manual about the practice of dry firing causing damage to the firing pin. Your thoughts?

    1 reply

    Most older rifles (circa 1960-70's) could be damaged by repeated dry fring (mostly firing pins breaking or, in the case of rimfires, the firing pin hitting the breech). Most firearms of good quaility made today (with the exception of rimfires aka .22LR) can be dry fired without issue.

    To remove a Berdan Primer, take a block of wood, drill a hole lager than the primer and smaller than the rim. Fill fired case with water, set primer over the hole you drilled in the wooden block, place a dowel that closely fits the neck of the cartridge into the neck and smack the dowel smartly with a mallet, hydraulic pressure will push the spent primer from the primer pocket.

    2 replies

    I have read that people use pencil erasers. I decided I wanted something more like the primer on a cartridge with real brass. Since posting this I have found and purchased snap caps for my rifle. Earlier I could not find them for my rifle anywhere.

    Great 'Ible. I used a section of pencil eraser in the primer socket as it's easy to replace when they become worn.

    3 replies

    I mentioned the pencil eraser. Does it offer enough resistance to the force of the moving firing pin? In my mind it seems the eraser would not be much better than dry firing without a snap cap. I could easily be wrong.

    The eraser method has worked well for me so far in both pistol and rifle calibers, I have noted however that some erasers are "tougher" or more "springy" than others, so I assume the type of eraser material used would be a deciding factor in the length of service. Oh and yes, I did notice your mention of the eraser in the I'ble, I was agreeing with you on that method. I'm also a reloader, and I color code the bases and "false projectiles" of my homemade snap caps with red sharpies to avoid the possibility of mixing them with live ammo.

    You could also carefully drill a hole through the case making it unable to hold powder and visually and tactiley identify your snap caps.