Thanks a lot you guys, I really appreciate all the helpful knowledge on here.
I ended up taking my Hornady comparator and running some leftover factory Hornady rounds through it, the same type of cartridge the brass came from. Turns out all of those 30 cases I ran through the sizing die twice are basically right in spec with the factory ammo as far as headspace measurement goes. Go figure! It made me feel better about them being safe to load and fire.
However now I'm still puzzled. Before I realized those original 30 cases would be okay, I setup my RCBS FL sizing die just per their exact recommendation in the manual- down to the shell holder, plus 1/8-1/4 deeper, and sized 40 more cases. What I'm finding is that they actually don't chamber that well in my rifle. I removed my firing pin, and chambered a bunch to get a feel, with most having slight and some having a fair amount of resistance when closing the bolt. I would have assumed if the die was setup per their instruction, these would have resized down essentially to easily chamber? I do understand good case lube practice, and even consistency in the press stroke can be at place, but I feel as though I do things pretty consistently. I did recently read you shouldn't lube the case shoulders which I had been doing, so maybe that has something to do with it? Curious on what you guys think.
Thanks again for all your help