22LR Snap Cap: Durable and Cycles Perfectly

Background

This is my 22LR snap cap model. Snap caps are a great way to test various functions of a firearm, practice handling a firearm, safely practice trigger pull without dry firing. I use them for precision long range practice on my CZ 457 at home--manual states not to dry fire--and to test magazine function on my 10/22 at home.

Yellow, #4-6 x 7/8in wall anchors are often recommended. They are great for cheap, repeated dry firing. However, wall anchors do not cycle in magazines the same way a live round or purpose-built snap caps do. They frequently get stuck and loading more than a few is unreliable at best.

There are purpose-built options on Amazon, for example. Unfortunately, they are relatively expensive. Rimfire snap caps are sacrificial wear items; they cannot last forever. If they lasted forever, it would mean your firing pin was suffering.

When printed in TPU, these snap caps cycle perfectly, are relatively durable, and will protect your chamber. See closeup photo in listing for examples of rounds I have used many times in my 10/22 and CZ 457.

Required Hardware

1. QTYx* - 22LR Snap Cap - 3d print “22LR_CCI_Std_40gr.” QTY is user's choice.

* I recommend printing these snap caps in batches of 50 “rounds,” so you can use your empty, old 22LR boxes to store them. Reference photo in listing for example of 50 snap caps stored in a Geco Semi-Auto case. Personally, I print in batches of 100rd to give to my friends.

Included in the .3mf is one batch of 5rd, grouped in one object for convenience, and one single round. Unforunately, Maker World would not let me upload 50rd batches, because of too many triangles.

Printing Notes and Material Choice

Please note that I can only recommend printing this model in TPU. I tried an initial print in PLA, and it got stuck in my chamber--I had to pry it out with a flat-head screwdriver. TPU's dimensional instability, or compliance as we call it, lends itself to this application. As well, the rim is necessarily thin, so TPU's elasticity allows it to take the firing pin's load without significant plastic deformation.

For print orientation, I recommend the striking surface of the snap cap (opposite the “bullet” end) positioned flush with the print. Reference the .3mf in case of confusion.

Other Notes

While the material properties of TPU lend themselves to this application, the rim is very thin and fatigue is a dominating factor in the life of the print. These snap caps are wear items, so you will need to inspect the rims occasionally. Altering the clocking of each snap cap about its central axis relative to the previous uses will significantly extend fatigue life. Remember that the firing pin only strikes in one location relative to chamber clocking.