Minor correction to all the good info Doug (alanint) has provided... "E.C.C.S.A PEN SA"
was not in Pennsylvania... the ECCSA was the initials for the company name, which I no longer remember, but I have seen reported on other forums that it was the importer name for the Cross Roads Gun Shop.
The PEN SA portion of the stamp (the space between PEN and SA was probably unintentional during the stamping process)... was a shortened version of PENNSAUKEN, NJ... the actual location for the importer.
Hmmm, I guess Rich got his post in while I was typing mine... 