The Behlen product is sold mostly by woodworking shops and is readily available from on-line stores. It's a wood finish product that Dr. Gaddy found to work well on case colors. It forms a protective film or coating that works to protect the colors from being worn off. Advantages are that it's easy to apply, dries quickly, doesn't impart any color of it's own, and is easily removed by lacquer thinner so a new coat can be applied later. Biggest issue is NOT to get it on the wood; it will damage just about any finish. As for the barrels, I guess you could apply it but bluing doesn't come off nearly as easily as cc. The lacquer wouldn't hurt anything, but it's probably not necessary. Not sure how it might affect the color/sheen/depth of the bluing.
