I don't like to use heavy snap caps for my guns with ejectors. I feel it is too much pressure put on the springs or in the case of my pre-1900 L.C. Smiths, too much pressure on the mainsprings.

I was using the cheap clear plastic ones with the spring in them for my ejector guns, but they started coming apart so I made my own.
This one is for 12 gauge and I also made some for 10 gauge. These are for non-ejector guns.

David