So what will weapons look like into the apocalypse? How much will be built by hand from things laying around and how much will be preserved from a time when industry had much higher standards than a guy taping a rock to a bat? In my journey across the wasteland of spam, porn, and small oasis of useful information. I have found some places that you should definitely check out and maybe begin to work on yourself.
One such place I found on the Post Apocalyptic Forums posted by dannyb0y999. It is a site showing many different Mad Max style weapons which frankly, you will need a tetanus shot to use let alone make!! But Mad Max isn't the only one to go into it's own fanciful idea's of weapons. If you have played Fallout 3 and ESPECIALLY Metro 2033 then you have seen that the idea for weapons when SHTF happens tends to be to keep weapons fairly simple. (following was gotten of of imfdb)
at the AirForce Talon Air Rifle. This is considered the most accurate and powerful air rifle around now imagine modifying it it to shoot larger ball bearings, darts, arrows, or bullets. A weapon that you just have to worry about getting rounds for and not about how your going to get it to you intended target. But of course some will want to shoot something with a lot bit more umpf. Which is why some people may try to start making their own rifles out of parts laying around. People already do it, if you have ever watched a prison documentary then you may have seen some of the weapons that convicts have made from materials at hand. Often they are ingenues and you have to ask yourself what these guys could do if they weren't criminals. Here are some guns that are homemade and often dangerous, but when they work are just a deadly as manufactured versions.
Sten a WW2 weapon used by the British forces as other insurgency forces in Europe. It is easily manufactured and there are at the moment many places on the internet where to get instructions on how to make them.
Obviously if/when the end of the world people will have many options on how best to hunt, kill, and defend themselves. It will take a while for post apocalypse weapons to start to become common. But there would be a day when people start making their own weapons, and there will be no shortage of possible weapons.