It's just a forming neck down on 30-30 . The shoulder is too long to get back in a 30-30 so there's little chance of a mistake that way . When formed from 30-30 it makes what's called a false shoulder on the neck . Size the 30-30 until it's a firm but not hard close in the action . Anneal to the bottom of the 30-30 shoulder after forming . Run them through the sizer again . Load a moderate load with a light bullet or 4-5 gr of a fast powder like Unique or Red Dot and fill the case with Grits , Cream of Wheat , or corn meal . The second means will do nicely but doesn't get all of the corners sharp . It can also be done in most back yards with an improvised pipe and bucket of sand muffler . The CoW and Grits will saw through cardboard boxes in 8' of 2" pvc so don't do that .

This isn't any help if you needed correct head stamp though .

You can look at Graff and son they have been good through this with keeping up .

Depending on what tools you have available they may even have Basic brass which is long enough for the 38-55 but just a straight case from the head to the mouth . You would need at least a 38-55/375 Win or 32 Special or Rem , a 30-30 or 308 and your 7-30 sizers .