Oxy-propane is fully capable of brazing fork crowns. While the oxy-propane flame is slightly cooler than an oxy-acetylene flame, it is plenty hot to melt brass and, in fact, delivers higher heat (as opposed to temperature) than oxy-acetylene, due to the larger propane molecule being burned. We used oxy-propane at Trek; I used a big "rosebud" tip to quickly heat massive parts like fork crowns and bottom bracket shells. At home now, I use oxy-acetylene, but my tanks can't deliver the gas volume needed to sustain a flame with the rosebud tip.