. I've put it into quite a few different firearms with distinctive calibers ranging from 7.62, 9mm, five.56, ect. Its ran flawlessly in each one. I didn't have to swap buffers or springs or just about anything. Just flip to 3rd placement and she or he's willing to go.. Thanks https://frt-triggers12455.digitollblog.com/36080641/frt-triggers-things-to-know-before-you-buy