What weapon mods are 11b allowed too buy and use?

I just completed OSUT and am now home for 3 weeks, just wanted too know, i know buttstocks, forward grips, and lights are allowed but what about magpul mags, a houge pistol grip, and optics such as EO tech or different Trijicon. Please dont relpy if your going too say dont buy anything cuz the military supplies everything, most service men know mil issued gear blows ex. Magazines, gear bags. and hey i have an Ar 15 back home so ill be using this stuff anyway after my 4 years expire. Im serving in the Army just throwing that out there. Id prefer replies from prior or current service men just due to the fact they would have more knowledge than someone making a guess from reading forums. Thanks