Very cool pipes! Wow!
So, the one dot places the pipe at 1924 or earlier, IIRC. Markings are consistent with that timeframe. No town name, just the model number, 51, and the US patent number, which begins with a 15 and ends in 20. I'm assuming that the initials, LJ, stamped in the side of the one dot are the owner's initials.
There are no pictures of the rims or chambers. I'm wondering if the pipe with the "M" stamp is meerschaum lined? Depending on whom you ask, town names began about 1928, or 1935. The Four Dot has the other common patent, which begins with a 15 ends in 28.
Stems look great! and look like the real deal as far as I can tell.
The model numbers might be helpful in narrowing down the timeframe as the numbers and the shapes they represented changed between the 1930's and the 1950's. In any event, they look amazing so are. The one dot is 1919-1924. The four dot may be anywhere from 1928 to 1946.