[Rigmarol]

I have met two separate men who both showed me their scarred thumbs. The scars looked almost identical. Both claim to have opened up their thumbs by pressing on a cap and it went off. Both now use a tool to seat their caps. One used a wooden dowel with a leather handle and the other used a carved antler or horn.

I'm a believer that it's probably not a good idea to seat caps with my thumb.
Squeezing is commonly done and I do it too to help keep caps in place.

There are those who claim it's dangerous but I say it's ok as long as you aren't seating squeezed caps with your thumb.