My only 30 cal mold right now is a Lee 309-170 that are finished with gas checks. Sizing is necessary anytime gas checks are seated. The mold i have was provided after submitting a quality claim. This same bullet from the bad mold mic'd 0.314" and I couldn't get them through a 0.309" H&I size die. Lee customer service was very good at promptly replacing the mold at no charge. They also must know how to pick a good mold. Now the castings measure 0.309 - 0.310". Lyman customer service isn't nearly as prompt. Expect to wait several months when dealing with them.
