I started with "Weapons" then went to "Firearms" to "Rifle" to "Modern civilian use" to "AR-15". I'm thinking the civilian AR-15 might suit my purposes but I want to double check.
I also tried ask.com using "old fashioned rifles", "old fashioned weapons", "out of use military weapons", "out of use rifles", and "1950s rifles".
Time: Mid to late 1990s
Place: Turkey in an alternative universe where the Cold War never ended
Characters: Two men who work as mercenaries who would know a lot about firearms and have regular access to top of the line weaponry (maybe even some weapons that were not used by major armies until later).
The idea is this: The two men have entered a terrorist camp and they are looking at their weapons stockpile. They discover the weapons are out of date and laughably worthless, "the modern day version of fighting with sticks and rocks." These could even be civilian hunting rifles. (Edit for clarification: When I mean "worthless", obviously these rifles should be functional for killing a man. But these terrorists are planning a coup d'etat, meaning these guys are expecting to go up against an army and take over the government using these weapons.)
Of course, they have to be lethal weapons (since I need one of the men to use one to kill three of the terrorists) and they can't be centuries old muskets or anything like that. So I need a rifle that's modern enough that the terrorists would think they're hot stuff but old and out of use enough for the men to think, "Where did they get these antiques?"