If your friend is planning on long-term (years-decades) storage, depending on how they are arranged in the safe cardboard boxes 'might' be OK, but I think of them as a way to get the gun from the factory to the dealer rather than for extended use.

Personally, I would use Renaissance Wax on the exterior surfaces, a light coating of Break Free on the internals, and Sack-Ups or Bore Stores for protection. Some form of temperature and humidity control and the guns would be set for quite some time.

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Alan
SWCA LM 2023, SWHF 220