The idea behind Snap Caps is you are able to safely practice firearm procedures without having to use live ammunition and to better simulate failures while practicing shooting.
I made these Snap Caps at the TechShop in Round Rock Texas.
Step 1: Step 1: Take Measurements
You will need to take measurements of whatever ammunition you are attempting to replicate.
Rim notch Diamter
Step 2: Step 2: Secure Aluminum Rod in Lathe and True Up the Material
I secured the aluminum rod in the lathe and made sure the diameter of the material was the same. I then made my measurement of the material thickness and started working backward to the thickest diameter my material would be when finished which is the (Case diameter)
Step 3: Step 3: Shaping the Rim
Next I started shaping the rim of the case. Using my measurements in Step 1 I knew the thickness my rim needed to be as well as its depth for the notch.
Step 4: Step 4: Finishing the Case
Using the Case Length measurement and the Bullet diameter measurement I finished of the case portion of the snap cap. I learned through trial and error it is better to have the rim part of the case closest to the chuck of the lathe and the bullet nearest to the tail stock. You will see in the next pictures how this will allow you to better use a file to shape the bullet for finishing.
Step 5: Step 5: Shaping the Bullet
Here I used a file to finish down the bullet portion and shape it as needed.
Step 6: Step 6: Creating Primer Pocket
Here I used a drill chuck tail stock to hold the near finished Snap Cap. I used the drill chuck to hold the Snap Cap because it has smoother chuck jaws than the lathe and I didn't want to mar up the finish. I will fill the primer pocket with hot glue or some rubberized product to protect the firing pin.
Step 7: Step 7: Test Out in Your Firearm
This was my first attempt and it wasn't to bad. I did file down the high spots on the rim of the case and chamfered the edges.
Inserted into my pistols magazine and everything seems to work great. With the Snap Caps made from solid aluminum they have almost the same weight as an actual round of ammunition and because they are not made from recycled live ammunition brass there is less chance of confusing these for live ammunition or worse yet live ammunition for your Snap Caps.