Actually that is crayon that I used to point out the markings better when taking the pictures. Originally these were "empty". This though is quite helpful, with the better contrast I came to the assumption (hope Roger can confirm) that even the same letters are slighly different, meaning that not only the rifle and patent number was hand engraved, but obviously also the company name. Quite a waste of labor IMHO.
Roger, any way to educate me whether this is an early or a late PPCo? Looking at my other PPCo it turns out both are for rifles in the T block. Maybe they did pick them in certain batches and therefore we are to assume some letters are to be seen more often as sniper rifles as others? Or just a wild thought of mine from looking at a handful scopes?