In a standard 10/22 rifle, these snap caps will last indefinitely. The firing pin spring in the Ruger is not strong enough to dent this material.
My primary business is selling thermoplastic resin, and I tested 6 different grades to find one that would work perfect. I tested the samples in every .22 rifle I could find, and one of my friends has an old pump action Savage with a wickedly strong firing pin. His Savage was able to rip through all of the other materials tested, but just leaves a dent in this material. I have used these snap caps at 3 appleseeds and have not had one failure.
As these snap caps are made from a semi rigid elastomeric thermoplastic resin, they are stiff enough to load and feed through most magazines. I have had only one issue in a well worn Remington clip, in which the snap cap would push up too high out of the magazine and the nose would raise up and this would cause it to jam on loading. The shooter changed to his second newer magazine and had no further issues.
I have attached the photo of the dent marks made by that pump action Savage. I shot one cap at least 40 times with that Savage, and even though it was well dented, the snap cap did not crack, chip or tear through.
I had neglected to include shipping and handling in the original post and have updated to include that cost.
Thanks,