BudsGunShop.com - SAAMMI?

Beto, The Sporting Arms and Ammunition Manufacturers' Institute (SAAMI, pronounced "Sammy") is an association of American firearms and ammunition manufacturers. SAAMI publishes various industry standards related to the field, including fire code, ammunition and chamber specifications, and acceptable chamber pressure.[1] Only manufacturers that are members of SAAMI are bound by the Institute's guidelines. (It is essentially an ammunition loading standard).

That will be a mouthful of an answer. Here is the link to the website: https://saami.org/technical-information/ansi-saami-standards/