Yeah. I used to toss out R-P 45 Auto brass because of the thin necks. I could resize them with my Lyman carbide sizing die (bought in the early 80's) about three times before they got springy enough that the die could no longer size them enough to hold the bullet. Even after two reloads, it would hold onto the lubed cast bullets so weakly that I could push them any amount deeper that I wanted to with my thumb.
Later, when I moved to a Dillon Square Deal B for 45 Auto, its sizing die's tighter carbide sizing ring would size the R-P enough to function. But by then I had moved on to buying and carefully working my way through bulk brass in the brand of my choice, so I still gave them away if I found them at the range. So, bottom line, if you want to be sure the R-P functions well enough, you may want to look at the Dillon sizing die. I think it is smaller because their presses are progressive and you don't want accidental rejects in the progressive process. It works the brass harder, but until the brass starts to split, it is good to go.