Tips to know when buying a Scar, new or used??

I should be looking at my first scar 16s here in a couple of days and wanted to know if there is any needed info that I should know prior to buying. Reason I ask is another forum member sent me a pm with info that I should be aware while looking at a scar. Any of you guys know of anything I should be aware of prior to buying or I should look for or at when I get one in my hands? This would obviously be really relevant in looking at a used one as well... thanks