I agree, I have 4 ARs of various configs and just bought a SOCOM so I would make certain I have a short rifle that will penetrate body armor if necessary. I have decided to keep my SOCOM for the same ammo as my M14s. I found that there is less than an inch difference within 200 meters between my match and army ball. (I have an ammo box of linked 7.62 from my army competition days, M-60. [3 time 6th army maching gun champion, [threefeathers bragging]) So I have two mags loaded with ball, a tracer as last round.
I keep two bandoliers of handloaded ammo ready so I can use it for my M1A, Savage Tactical, or the SOCOM.
I keep two bandoliers ready for the M-4s, each ready rifle is in a UTG soft case. Each soft case has an emergency handgun in 9mm because that is the caliber the military has.