Flints from different brands aren't equal for sure. For example, Zippo flints are noticeably softer than IM Corona's. They seem to produce more sparks and don't last as longI thought all flints were equal. Are some flints better than others?
Even being soft, Zippo flints managed to dull my sparkwheel in 3 years. I haven't heard of similar problem with Old Boy lighters. From which I deduce that Tsubota (who produce Peterson lighters) use softer metal for their sparkwheels than Corona does.
I dont know, if Peterson sell any flints under their own brand and which brand they recommend to use with Peterson pipe lighters.
The flint compartment tube in my Peterson lighter looks pretty wide, wider than in a Corona, so probably the "thick" kind of Dunhill flints would fit it best. I haven't tried them though as Dunhill flints aren't sold where I live now.