Welcome to the forum Scott!
Is it possible to include pictures of this marking? I am not familar with the letters pse on a barrel, but there are many variations? Is it possible that it is an import stamping?
Further information would be very helpful, such as type of gun. Can you tell us any markings on the gun?
Proofs? (see on your left under tech information if you came through
www.lugerforum.com) Tell us what and where proofs and markings are located.
There are forms in this section, where you can print out and then write down pertinent information.
What serial number is on the gun? To include any letters next to or under the serial number?
What year or letters are stamped on the top of the receiver?
What initials or letters are on the toggle?
Can you provide pictures, to include side, top, etc?