I've looked all over, but I guess I missed the RCBS mold.
It actually works slick as a whistle. I tore a few when I first started putting them on the boolit cause they were already sized and lubed. I figured out that there was no lube in the sizer. Now I just run the boolit thru once for size and lube then take the boolit out, put a gas check on it and run it thru again while lubing again. That eliminated the torn checks.
It works very easily really. Using pop or beer cans with thin metal makes the checks slip on pretty easy as long as you size and lube first. Otherwise there is to much stress on the check and it can rip.
It does swedge the base of the boolit a little, which I'm sure would be easier to do with fresh boolits like Pat says. I'm using 1 month old ones and some 8 month old ones and am not having any trouble now.