I bought my TC Hawkin 50 Cal new in 1989 from Gander Mtn. All I have ever used is Bore Butter to protect the metal after cleaning with warm soapy water. I do squirt a shot of wd40 in the nipple hole before replacing the nipple after cleaning. Has worked fine for 30+ years.

A true sportsman counts his achievements in proportion to the effort involved and fairness of the sport. - S. Pope