Will I get a copyright strike or something if I use a picture of a weapon and the name of it? (e.g. a shop where you can buy guns, AK-47 with the pic)
You most certainly can get into legal issues in the US. Weapons names are often trademarked and their appearance could be copyrighted (there is a difference between trademarking and copyrighting. See here http://newmediarights.org/guide/legal/Video_Games_law_Copyright_Trademark_Intellectual_Property). Recent debate about it has been growing recently, though.
EA had either paid or made agreements for the right to use real weapons in their games for years, until recently they decided to stop doing so, invoking the First Ammendment of the US Constitution. They have claimed that "We're telling a story and we have a point of view. A book doesn't pay for saying the word 'Colt,' for example". See full article about that here: http://kotaku.com/ea-wont-be-paying-for-real-guns-in-video-games-anymore-494940003
However, such decision followed after they were taken to court by a helicopter makerfor using their helicopter models without autorizathion. And regarding this process EA quickly settled an arrangement to stop the judicial struggle: http://kotaku.com/ea-ends-first-amendment-claim-to-use-real-world-helicop-1159651214 Which means, they gave up on part of their claim.
Of course that for the companies that make weapons, their use in a major game can bee sen actually as free advertisement. So instead of monetary compensation, sometimes agreements can be put in place. See: http://www.reuters.com/article/2013/05/07/videogames-guns-idUSL2N0CS2A220130507
So, as you can see, the common practice has been to need to be granted the right to use copyrighted and/or trademarked licenses for using real weapons in games. Therefore, before there are noticeable changes in the judicial interpretation about it in the future (if it ever happens at all), it is good to take precaution.
That is often said to be the reason why so many games only go for very generic names of weapons and the descriptions of their details.
Disclaimer: I am not a lawyer and since here were are mostly programmers, most people here won't have the technical expertise for a fully detailed technical answer.
I think they are, even if they are not because of they are trade marks (usually marked with TM), it may cause problems if you sell your game with these names in it.
Thus most games use names that reminds of original, like "fanas", instead of "famas".
Disclaimer: These informations are not legal advice or equivalent. You should ask a lawyer for a legal advice. I'm not responsible for any damage caused by this answer.