Photographer and open source software fan.
I’ve also made a few tutorials at http://youtube.com/@AnAustralianPhotographer
Blog: https://anaustralianphotographer.wordpress.com/
Webshop: https://anaustralianphotographer.threadless.com/ where you can buy prints and other merch featuring my photos.
Calibre conversion kits do exist. I think they could be for might be cases where people want to practice marksmanship with smaller calibers like a .22 https://en.m.wikipedia.org/wiki/Caliber_conversion_device