I took my time, took union breaks, and had the lower complete in less than 2 hours. I was kinda surprised "that was it".
The upper was even easier.
Like a good old American car,....keep it simple.
Same with my M1 Garand,.. Designed to be serviced, torn down, rebuilt, repaired, in the field with tools the soldier would have access to.
My teenage son, had my AR and M1 disassembled, and than reassembled while listening to my old Emerson Lake & Palmer albums...

Oh, What A Lucky Man, He Was....
Good shooting BAC, enjoy it.