We simply wear the rust off with constant use, before it takes hold!

Seriously, I make up a concoction consisting of equal parts AlCom No.2 Waterproof grease (un-coloured), and good-quality German light machine oil. The mix is shaken vigorously until a single honey-like consistency is achieved (takes a while!). Apply with soft cloth.

This stuff stays put no matter what, is perfect for barrel-channels under the stock, repels heavy rain, and lubricates working parts. I don't use it in the bore, though it would obviously be fine for that, but I prefer Sweets Oil 'cause it seems to lift any residual fouling while preventing rust.

I have carried many of my rifles including vintage doubles through some spectacular tropical down-pours, with no ill effects whatsoever. Most British hunting rifles were designed and built for hard work in the far-flung out-posts of Empire, bit silly treating them with kid-gloves today!