A peterson dating guide
The tenon is slightly tapered so even if the briar or the stem material shrinks or expands the stem can still be inserted tightly.
This allows to safely remove and replace stem while pipe is hot.
The first two escutcheon in Peterson's genuine silver hallmark are a Hibernia and a Harp.
The first mark on the band of this pipe is a Shamrock denoting a non silver metal, probably nickel.
These faux hallmarks cannot be of any help to date the pipe.
It is all part of the unique Peterson ownership experience!
When in doubt, study my late, great, old friend Mike Leverette's marvellous reference work, The Peterson Pipe Project, “A Peterson Dating Guide; A Rule of Thumb.”The "Made in Ireland" block format evident on this pipe can be a headache in dating Peterson pipes, since this same stamp was used in the late Patent Era as well as the late 1940s.