What replacement barrel is this?

[OD#3]

A 1940 42 code I ordered from Simpson's arrived yesterday. It was listed as all matching except the takedown lever, sear, and magazine. But the barrel looks to be a replacement of some kind. Its only marks are three capital letters on the bottom near the breech arranged in a triangle with "E" on top and larger font "P S" under that. Irritating. Everything else was well-represented, and I new I was getting a shooter, but I would have liked to have known beforehand that the only reason the bore was in "excellent" condition was because it was a replacement.