As I said in an earlier post I have ordered a RRA Varmint Rifle with 20 inch barrel. I have never previously owned an AR15 of any description. Can other members advise if there is anything important or otherwise I need to know bearing in mind all spare parts have to be imported here in New Zealand.
STI

The only part that broke on me was the extractor, but then I don't shoot very much.  I had bought some spare parts but they're mostly for the lower, I've never had to use any of it yet.  I have spare bolts, lots of triggers, hammers, sears that never get used too.  I think it's a good idea to keep spare springs, detents and rolled pins for the lower receiver around because the lower has so many of these little springs and detents that like to fly away and never to be found again.  Also get an armorer's wrench.  I bought one in 1999 and never had much use for it until I started assembling uppers on my own, it's a great tool for removing/installing flash suppressors, buffer extension tubes, etc. even if you're not planning on putting together uppers yourself.