I believe a mingling of straights made in the same State and otherwise meeting labeling standards (less than 4 years must have an age statement) can be labeled as Straight Bourbon.
I was thinking it was a mingling of different 4R mashbills, but not different distilleries.
To get back on topic, this is one reason bourbon is getting worse...Too damn many mystery bottles...
"Every bottle is its own learning experience." -- Sensei Ox-sama
Biggest factor, IMO, quality of the cooperage has taken a huge dive. Fully yard-aged wood used to be the norm, now it's a rarity.
At times regular bulleit may have been 100% 4R but they could not say for certain that it is now 100%. I don't know if that means if it is distilled at different places, then shipped to be barreled and aged at 4R or if the filled barrels were brought in from outside sources, aged at 4R or if diagio simply bought aged stock elsewhere and it is blended in.
Col. Charles K. "Crotchety" Cowdery
"Whiskey Don't Keep."