From looking at Jent's picture, picture #5 with 3053 on it. Notice that on the bottom front, there is a slant to it. Not all pre-13 guns have this slant. The early Fulton guns, up to sometime in 1893 have the straight side not slanted.
If your does not, I would see if they could make it squared for you.
FYI, there are also some post 1913 Regular frame guns that have the slanted front.