Re: best browning for flintlocks
I like the Birchwood Casey stuff that goes on a hot (warm) surface, Rub it on with a swab and then after a few coats, scrub it off with 4 ought steel wool.
When oiled it looks as smooth and shiny as a blueing, just that it is dark brown in color.
Old timers would scrub the barrel with a little salty water with perhaps some egg or soap in it to make it cling to the metal. Place it in a warm humid cabinet and then scrub it down daily. Recoat and then repeat, until the desired effect.