Should be just 45 COLT on the left side just in front of the frame.
#325,000 is generally considered the start of 1913.
Lots of changes in the 1913 to early 1920's Colts as far as markings. But one thing stayed the same as the 1900-1912 guns and that was the caliber marking(s) style.
FWIW,,the the 1913-early 20's production included the SA's that got fitted with the converted Model 1878 DA Model cylinders,,,the so called 'Long Flute Cylinder' Colt SAA's.
Yours is probably a bit early in the production for it to be one (thought to be around 1915), but you never know.
Easily recognizable as the cylinder flute cut extends behind/to the rear of the locking bolt cut. On a standard cylinder, the flute cut is just about even with the front edge of the bolt cut.
Also the Long Flute cylinder has a shorter than normal cylinder bushing,,about 3/4 the OAL of the cylinder itself.