Resisting the urge to get a 5.56 lower and just invest in ammo for what I have now, KISS theory. One rifle, one shotgun, one pistol caliber.
Have stayed with two prime centerfire calibers all this time, fighting the urge for a "standard" caliber AR build as that just means yet another caliber to have to find room to store. Firgured shotgun would most always be somewhat available, at least from what I see at Sports Auth.
Wife's little .380 need some good defensive loads, and that stuff is hard to find locally. Luckily, her ammo gets stashed in her closet.