I'm shooting a Lyman 240gr flat nose (4 cavity # 429667) that drops at .430. Never slugged the bore on my Marlin 1894. Shooting these over 6.6gr of Unique which is a pretty mild load for Lever Gun Silhouette. BTW this is for 44 mag. Never tried any 44 specials in this gun even though I do load some for my wife's pistol. May have to try some in the future and see how they do. I'm thinking if your trying to stay 1250 fps or lower you probably don't need the gas check. Just one extra step that is not needed at those velocities would be my guess.