MagMarc,
I believe they were.
I got curious after Dick Dietz told me in the early 90's that the original heavy-sidewall Core-Lokt PSP had recently been given a thinner jacket. Looked at some of the ammo on hand and noticed the bullets were more "pencil-pointed" (as Elmer Keith used to put it) than Core-Lokts I was familiar with. Pulled a "140" from a .280 and sectioned it, finding the little Interlock ring.
I shot a number of animals with the original heavy-sidewall Core-Lokts with good results, especially the 100 6mm, 150 7mm and 170 round-nose for the .30-30. But that was a while ago.
Haven't sectioned any of the round-nose Core-Lokts in a while, so don't know if they still have the heavy sidewalls. They did, long after the jackets had been thinned in the spritzer models.
