adhesive on my barrel

I bought a Hoghunter in 308 & removed the iron sights. There was some kind of adhesive under the iron sights that won't come off. I had to tap the sights off the barrel with a small hammer to break them loose. Has anyone ran into this before & if so, what did you use to clean the barrel? The last thing I want to do is ruin the finish on my new rifle. Thank you for any information

Have you tried Acetone?

Acetone would probably remove the adhesive as mentioned by Rosco. You can also take an old used up rifle casing, flatten the neck with a vise and use that as a scrapper it will not harm the bluing. Any brass left on the bluing will clean off with bore cleaner.