@OP...All the FN barrels are going to be good whether you get them from PSA or Noveske. All of them will last for at least 30,000 rounds and accuracy wise, they will all shoot less than 2 MOA out to nearly 300 yards.
Some FN barrels are nicer than others in terms of quality control and spec. The difference in price also comes from what the barrel reseller is demanding from FN in terms of rifling tolerance. Lastly, the gas port size will obviously be different depending on which FN barrel you get.
The FN barrels I know of come from:
PSA
Spikes
Noveske
Centurion
Rainier
Personally, I'd spend my money on the Rainier, Noveske and Centurion. All three of these are as nice or nicer than any other CHF barrel available on the AR market. You can't go wrong with anyone of them.
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