J Barnett was the Chicago mobs man. The Jerome was a mail drop. We know of no gambling there. Literaly tens of 1000's of different chips from different distributors shipped there over the years.
Chips were use at the OWL Club in Calumet City, IL. It was a huge casino.

This info from John Binder:
"Joe Barnett was a member of the Chicago Heights (south suburban) Crew of the the Chicago Outfit. And an employee of the Owl Club, a crown jewel of a gambling place. I have a check made out to the Owl Club which is endorsed on the back by Joe Barnett and several of the other employees.
John Perry started it as a little place in Cal City. Then guys like Accardo, Ricca, Campagna and Frank LaPorte came in as his partners and it went big. The JP are his initials.
I once showed some JP stamped chips (there are multiple varieties delivered to Joe Barnett, etc...) to an old time gambler who worked at the Owl. He said "Owl Club. John Perry."