I've seen on this forum that a lot of people have ak's, sks's, and ar-15 series weapons. I'm 15, and when I turn 18 I am going to buy a couple of firearms. The problem is, I live in California, home of gun restriction laws. If some of you guys could try and help me out as to find something with stopping power that isn't illegal here, that would be great.

Same here, i'm 15, live in California. California pretty much bans all assault weapons. Here is some pages that might help:

First, hangun/shotgun law:
http://crime.about.com/od/gunlawsbystate/p/gunlaws_ca.htm

Second, illegal firearms, pages 11-17 are helpful.
http://ag.ca.gov/firearms/forms/pdf/Cfl2006.pdf

I could be wrong though. You could also ask anyone that ones a legal firearm dealership. Its kinda confusing. The only one that is ALWAYS banned is the Barrett .50.

The SKS was only recently banned, because it was very easily modified to fire automatically (most guns can with a little knowledge). As with any gun, they can be grandfathered in. Because the ban was recent you can find prebans all over the place for very cheap prices. There are plenty of other SKS variants available, as well as other "assault" weapons that are uncatagorized on the official banlist. There have also been a load of new AK recievers that were made specifically to loophole the ban, though I have no idea how expensive or difficult to get they are. To put it simply, California's attempt to ban too many weapons has resulted in tons and tons of loopholes concerning what is and what isn't an assault rifle, and therefor they couldn't just say "all assault rifles are banned", they had to form a list, litterally containing every make and model banned in the state of California. They generally go by make>reciever>year thus making it easy to find a legal reciever and make your banned rifle legal (though please note doing so MUST be done legally and in a legal state, don't get yourself thrown in jail)

Going to gun shows, you'll see a lot of people selling legal SKS variants and old Mausers, but not a whole lot else for a decent price.

If only the handgun banlist was so lucky, hardly a single loophole at all, if any. Its pretty much air tight.