Well, I don't think it will be the dies, per se, but how you crimp and reload them. Use minimal case mouth flare before seating, and use a HEAVY crimp after bullet seating (crimp separately from seating). I knew of several experienced reloaders had issues with the 357 Sig. Some common problems are the case shoulder buckling during bullet seating if you try to keep the neck tension too tight. If it's too loose, the bullet wants to move, so a heavy crimp is needed. All the major die mfg should be about the same for sizing, but get a good Lee factory crimp die, or similar crimp die to run. You will need to play with the loading process to make sure you can not move the bullet at all after it's loaded. The 357 Sig is a very high pressure round (38K to 45K psi, depending on who's numbers you go by) and will be +P+ easily if the bullet is seated deeper by being pushed into the case. I won't reload this round for this reason, and the varying cases of 357 Sig.