"PR" etching in deadwax?

I have a ton of LPs, most of them red-and-green Atco pressings from the seventies with "PR" etched in the deadwax. Does anyone know who this "PR" is, and what have your experiences been with this work?

 

Presswell Records in NJ. They pressed a lot of Atlantic stuff. If you do a search on "Presswell", you'll probably find more info if you're interested.

 

Do you mean red & green Atlantic?

 

Hi,

Presswell Records in Ancora, NJ pressed these. The main plant that served the East Coast market and common here in Eastern Tennessee.