Laurel Mountain Forge's solution puts a brown finish on brass.
But you should be browning the barrel clean of sights. With sights installed, it will be nearly impossible to not get a puddling of the solution around the sights. It will not be an even brown with sights installed prior. Underlugs, staples, or loops is a different matter. They are on the bottom flat where it is not nearly as important.
To answer the question though, try a little on a Q tip on some clean brass and silver, and see what happens.