Jameson Black Barrel is one of their "select reserve" whiskeys. The "black barrel" label appears to come from the aging in "flame charred" bourbon barrels and "toasted" sherry casks. They age a blend of pot still whiskey and grain whiskey, the latter they describe as "rare, sweet, and not found in any other Jameson whiskey." The bottle experienced a redesign in 2016 (dropping the "select reserve" label) but had no formula change.
Founder John Jameson acquired the distillery in 1780... by 1805, Jameson had become the world's number one whiskey. While considered a blended whiskey (malt whiskey blended with corn whiskey to sweeten and the lighten the flavors), Jameson prides itself on producing every component from "grain to glass"--the blend is a blend only of married Jameson whiskies. The Jameson distillery has long been closed while the brand was produced for a time at Powers and now the Midleton Distillery. Irish Distillers--the owning company--was purchased by Pernod-Ricard in 1988.