Some outtakes from a gun forum of which I am a member regarding someone who thinks there was a lump of Loctite in the sight channel on his revolver:
Original Poster: "Hey i removed a scope from a S&W 29 and there seems to be a small lump of what i think is Loctite in the rear sight channel. I dont want to scrape it off and damage the blueing, what will dissolve that stuff?
Reply: "What color locktite is it?"
OP: "I don't know! I know my dad loved the stuff!"
Another Reply: "How can you not know what is the color, you said you see a lump of it! So, what color is the lump? If it is Red or Blue Loctite, it should be red or blue respectively as it points out on the Loctite website...As I said above, their epoxy compound dries metallic gray."
No further replies so far from the OP.
There were many other replies overall, most explaining how to remove it and the gun gurus (including yours truly) contradicting one another but the OP never got back to answer that simple question. My guess is the OP tried to pry off the lump with a fingernail and off it came whatever it was. It is just hard to imagine though that someone could not tell what color was it - unless of course he is color blind; he also never got back to say whether or not he removed it.
All the best,