So do you think they are referring to the barrel or the bolt? Browning’s website talks about their bolts being stamped “NS” ."Winchester introduced the Nickel Steel barrel alloy in early 1895 (with the introduction of the 30 WCF). It was the standard barrel alloy material for all Model 1894 barrels made for the 30 WCF, 25-35 WCF, and 32 WS cartridges until early 1932 when Winchester switched to Proof Steel as standard."
I don't believe this is a fair summary.In today's world, it has no meaning from a practical perspective. A non-nickel part will perform identically to a nickel containing part. It doesn't affect or improve the steel in ways that are meaningful to a barrel, bolt, or receiver. At least not in a way that is better than the other alloys commonly used for those parts.
Jeremy