The Brahma hen "neck" has small hackles but is not a good substitute for Partridge. The neck feathers are more like a badger or furnace hen hackle. The necks do include side feathers that have markings similar to partridge. Some of these side feathers will be in the 12 to 14 size range. The saddles have nicely marked feathers but are mostly larger.

Although I like the Brahma hen saddles a lot, and they make great soft hackles, IMHO nothing really looks like Partridge.