We all have them, whether they are family heirlooms or picked up at a yard sale, guns that need to be retired and hung on the wall.
I still have the first gun ever given to me, an old .30-.30 Winchester model 94. My friend Paul George gave it to me while I was still a little brat tagging along on deer hunts with him and my dad. I love that old gun, and I've carried it hunting more times than I can remember, but there comes a time when you need to hang up your old heirloom guns and move on to something new.

By Tintype (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html), CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/) or FAL], via Wikimedia Commons

By Mikehelms - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=26980450
Oftentimes with older firearms, it is difficult to determine exactly what type of ammo they take. Sure, that old pistol you found in your grandpa's closet is a .22 caliber, but is it made for smokeless powder? It's better not to chance it and keep it for looking rather than shooting.

By PHGCOM - Own work by uploader, photographed at Yusukuni Jinja, Public Domain, https://commons.wikimedia.org/w/index.php?curid=7354020
As with any metal, rust is a constant enemy of firearms. Rust and repeated rounds fired over the years, cause the barrel to become worn and pitted. This can cause weakness in the metal. Any firearm that shows significant pitting or rusting should be on your wall and not in your hunting blind.
Aside from something being wrong with your antique gun, some are just too awesome to use in the field. Whether it fires or not, some guns don't belong banging around in your truck. Some are just too cool not to be wallhangers.

By Arthurrh (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

By Fish Cop (Own work) [Public domain], via Wikimedia Commons
NEXT: 10 THINGS ALL LEFT-HANDED SHOOTERS WILL UNDERSTAND