U.M.C. Ledger entry

Can anyone enlighten me on the following entry that appears under a number of shotshell types and gauges in the U.M.C. Ledger?: Commenced using spring in header. Seems to me this pertains more to the machine than to the shell so I’m wondering why they found it of sufficient significance to enter into the ledger.

Probably the main man told the ledger keeper he regarded this as worth recording in the ledger and the keeper followed that clear lead. Jack

Would the spring be used to eject the case from the header?