I love waking up an old thread!
I bought this same mold, the Lee C324-175-1R. It has driven me nuts. I couldn’t get my checks to seat properly. The sage/gator checks were to small. I made a punch to enlarge them. I tried seating them nose first. I tried base first. I tried sizing first, then seating the check, both ways. I tried annealing. I was destroying half my boolits. The half that survived were sub standard.
I gave up this weekend and drilled out the mold to be a plain base mold. I’m happy with how it turned out. A little rough on the finished bore, but concentric. I think that I can get these boolits to shoot ok at slower velocity, about 1200 FPS.
I have an Ideal 311291 that works great with gas checks and the Lee sizers. I knew that it could work. I knew I wasn’t crazy.
Reading this thread was cathartic. I’m not the only one! This mold is a problem, when used with Lee sizing dies.
I have an NOE 325365 five cavity coming in the mail. Fingers crossed!
JM