My oldest firearm, which is a newborn compared to some here on this thread, is a 1947 Marlin Model 90, 12 gauge O/U...Bought it at an auction when I was 16 for $50. I've shot a lot of partridge, woodcock (ehh, ehh, ehh, he said woodcock ) and squirrels with this thing over the years...
My oldest is a relatively young pup .. 1945-born Mosin Nagant M44 carbine. Not the prettiest girl at the dance, but she definitely turns a few heads when she "sings"
Winchester 1906 .22LR, made in 1913. It was my uncle's before it was my dad's, and is the first gun I ever shot. Not long for me through - it's heading along to my nephew in the next week or so.
My oldest is a 1918 produced Colt 1911, which likely saw combat in WW1, where my grandfather manned coastal batteries in France. He was lucky to avoid the trenches.
My 2nd oldest is a 1943 Colt 1911A1, from WW2.
I couldn't find a pic of the 1918 version, and I was too lazy to take it out of the safe, so here's the 1943. The slide has a serial number behind the firing pin retaining block which matches the receiver.
I also have two U.S. M1842 muskets. One is a relic and hard to see the date but it looks like 1846. This one, from 1850 I cleaned up and used it as a Civil War reenactor for a while.