Im only 24 so most of mine are 3 years or newer. The oldest I have is my Sig P-228 that I bought new in 2009 i think. Well over 1k rnds and still dead on. The newest is my Kimber Compact Stainless bought in December of 2011. So yeah just a few months ago. Already 500+ rnds and no malfunctions of anykind.
It varies depending on function or destination. Usually a Springfield 1911 A-1 in .45 ACP with some goodies. Bought new recently. Sometimes a charter Arms bull dog alloy 5 shot in .44 special. Bought new this summer.
My oldest is a 6 inch S & W pre-M & P model. It is a real fine shooter and tight as new. 3 to 3 1/2 inch groups at 50 yards of of bags....158 gr. swc at about 925 fps....A plus P load...
Glock G19, not super old but been around for several years
Ballester Molina 1911 style 45, made around 1940, shoots great
Colt 1911 5" Government model, bought last month