So ... looking at lengths and compactness of the rifle (I borrowed this from a stranger.... not mine)
Overall length, stock extended is 36"
Overall length of the lower receiver stock extended is 18 1/2 inches
Overall length of the lower receiver with stock collapsed is 15"
Overall length of the upper receiver/ barrel is 24 1/2"
Barrel length with flash suppressor is about 17"
So
If length is a factor, unless you're running a barrel that is shorter than 8" (collapsible stock) 10" with an fixed stock, then you won't get a shorter part than the upper and barrel....
Just breaking it down at the designed points vice disassembly