Lebiediew

Hello I went through the game. Now I've got trophies, most of them got done, but I need to do everything for 100%. Now, I skipped one weapon (from the Calloway mission), can I somehow go without it? if I do everything and from the new record I will find this weapon it will pass me? because I do not want to do it all and then it will turn out that I will do the same.