I'm building an ar and down to the bolt carrier group for the final part I need to buy. I've put it off because I'm not sure what to go with. Should I look for a used one or just buy the cheapest new one I can find or spend a little extra on a chrome or titanium one? I've never had an ar before so havnt had experience with what breaks down or not. I'm building my ar for target/long range shooting. Not any close quarter stuff. Thanks for the inputs