I am searching for any evidence the headstamp SPC, or S.P.C. appears on any caliber other than 9x19mm. There is evidence that some of these 9x19 were made by or with the support of DWM. Other 9x19mm with this headstamp code clearly were made without DWM direct involvement.
It has been reported that these rounds were made by a company that produced shotshells until at least the late 1930s.
Perhaps shotshell collectors can help solve this puzzle.
Any help would be appreciated, even evidence of this headstamp being used on other centerfire calibers.
PS: A related question. One of the boxes for these rounds (the one not related to DWM) has impressed the marking “M & S 1937” . Does anyone recognize this box maker. If so what other ammunition did he make boxes for???