The problem with one of those "Stepped" chambers is the end of the shell does not just enter the forcing cone, but actually goes into the bore proper. This both gives an extreme reduction in size for the load to pass through but also slows the opening of the crimp, both conditions conducive to "High Pressures". On an older gun always examine the forcing, if it is very short & abrupt "Do Not" use shells longer than the actual chamber length (After Firing length)
.
Using the longer hulls is based on a forcing cone with a minimum length of around 3/8" & most are around 7/16" to ˝" long.
