I like the Triple-K snap caps. I found the A-Zooms to have so much
excess headspace (at least in 44) that they did not really contact
the firing pin. Consequently they really do nothing.
The Triple-K is plastic with a brass "primer" and a spring inside.
They provide a lot of strain relief and have a nice "sproing" sound.
They don't last forever but do the job of providing ease of mind
when dry firing a lot.

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Nemo