I don't doubt that NEF proofs their guns. They are affiliated with Marlin who also proofs every gun. Of course, so do Winchester, Remington, Savage, and, yes, even Ruger. I would venture that Ruger has done as much and probably more when it comes to pressure testing their arms than do most manufacturers. Evidence of proof firing can be found on virtually any factory rifle in the form of the proof mark located on the barrel just forward of the receiver.
