I have the exact same problem with the Forster seating stem. They will develop a small crack and seize when seating and grab the bullet. They're very thin, and hard. I cracked my original for my 300 win mag and thought it was odd, and maybe I got a bad one, or I did something wrong. Second one cracked so I bedded it with devcon. Purchased one for my 223 and had the same problems. Not seating fast, annealed brass, not compressed loads in the 223, maybe 100% fill in the win mag. That's why I gave the LE Wilson a try. You just need an arbor press to use it. Or anything big enough to fit the die in to squeeze it. I'll be purchasing more.