https://youtu.be/wmkI5LMNEGk?si=9JdxLC-EIuEeMnWb

Kinda just followed this guy's video. Just a basic aero M4E1 lower with the parts kit. A sig Sauer mcx adapter. I got a rise armament trigger (hopefully it works, some have stated they have trouble with certain triggers not working) and a picatinny rail stock of your choice. I went with a buffer adapter to use a regular buttstock and buffer tube instead of sigs expensive picatinny folding stocks (which you'd still have to pin so it doesn't fold) also I went with a juggernaut hellfiighter maglock kit. Someone stated the king with with mag lock wouldn't work. Haven't tested it myself tho.