My 15-22 came first. After that, I've spent over a year deciding on what to get in the 5.56x45 / .223 Rem and I ended up doing TWO things.
The first was to re-work my current 7mm T/C-U (circa 1981) to a 23" Stainless Steel barrel, 3-9X42mm scope, and composite butt-stock and forend. I actually shot it for the first time on Saturday and being this is my first real scoped rifle, I know I have a long way to go but the recoil on .223 was not bad for a single shot so I can only imagine my SECOND firearm in .223, which I will pickup tomorrow, a Colt LE6920CMP-B (Black MOE). I'll post pictures of it this week but here's my current two long arm:
and just picked it up today (3/13/12):