I used Evap-Rust in the bore of a barrel.
First, I let it sit for 10 minutes (I am the impatient type). There was little to no effect. Next, I let it work for 1/2 hour. Most of the spots of rust were gone, perhaps 80-85%.
I was very careful to avoid getting it on the outside of the barrel or on any other part of the rifle.
Ron
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RonC
Outside of a Dog, a Book is Man’s Best Friend. Inside of a Dog, It’s Too Dark to Read. Groucho Marx (or possibly someone earlier)