NiB is a good plating in many applications, just not on BCG’s.
I have no issues with NiB on AR barrel
extensions. Never seen or heard of it causing an issue there. The Ballistic Advantage Hansen barrels are my favorites in the under-$200-category. Nitrided, NiB barrel extension, and pinned gas block. Make sure to check the port for proper sizing, and the gas block for alignment. Typically sell for $180 or so in the 16” length.