All markings are shown on the same scale to make a better comparison.

There are two different J-M markings. The one on U-241A (made by Pittsburg) and M-3161 are identical. They are about 1-7/8" long and the letters are 3/16" tall. The J-M on M-2052 is smaller. It is 1-3/4" long and the letters are about 1/8" tall. The font on both types are essentially the same with only slight differences. M-2052 and M-3161 were made by New Lexington.

The font in all the New Lexington markings is essentially the same as the J-M markings with only slight differences. The serif marks appear to be a bit longer with those on the "E" nearly coming together. All of the New Lexington markings are about 1-5/8" long and 1/8" tall.