http://firstwefeast.com/drink/pappy-van-winkle-bourbon-facts/
Just for your FYI -
"So what's the story behind this liquid gold? Based in Frankfort, KY, the Old Rip Van Winkle Distillery is not actually a distillery at all, but rather a company that contracts the production of its coveted spirits to Buffalo Trace. Julian "Pappy" Van Winkle, for whom the bourbon is named, started selling whiskey in 1893 as a salesman for W. L. Weller. He would eventually go on to become the president of the Stitzel-Weller Distillery, which produced many well-respected whiskeys through the 1960s. However, years after Pappy passed away, stockholders forced the sale of the distillery; to keep the family tradition alive, Julian Van Winkle III and his father started buying back barrels of their own bourbon and bottling it under the Old Rip Van Winkle label (some of which is still being sold today)."
Buffalo Trace cannot produce enough neutral spirits on it's own to keep up with demand, hence why they are buying it. Often times, the internal and external are blended together.