Rings won’t fit in grooves on pistons.. HELP!

I’m partway through building the bottom end of my 383. I was just about to gap the piston rings but when I test fit them they won’t go in the grooves on the pistons…

Do I need special rings or something? 30 over TRW L2293 dome pistons and Hastings 30 over moly rings.
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You need new pistons, don't use the same old ones.