Which instructions are you following? One from Angier, or perhaps the Parker Process? The reason I ask is that I've experimented with the "Preheat" technique before applying solution, and can see no advantage to it over drying the barrels with a heat gun after application. It can actually cause over application of solution in spots, creating faults, especially along ribs and at the muzzle.

Ken

I prefer wood to plastic, leather to nylon, waxed cotton to Gore-Tex, and split bamboo to graphite.