If your budget is $600 either save some more or buy something other than an AR. Cheap AR's tend to have issues. For a couple hundred more you can get a Bushy or Colt from CDNN, or find a good one here in the marketplace. There's also building one yourself and buying quality parts on various sites like here and the EE on ARFCOM. Otherwise, look for a used Arsenal SLR-106FR. It's a 5.56 AK that would serve you well.

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