The CAS was likely not shooting heavy loads. Especially with leading in the cone, sounds as if he may have been using "Too Hard" of bullets. A lead bullet too hard for the load will not "Bump-Up" & seal the bore allowing gas cutting. I forget the exact number now but general rule for revolvers is to multiply the BHN by 14xx to determine the pressure required to bump-up the base of the bullet. In reverse if you are loading to a pressure level dividing by this number will give the max BHN which will bump-up. Many bullet makers only sell the hard bullets & they're not always best for the loads used by CAS.