Are Dimensions In Scott True? (Uc14 Vs. Uc15)

I have two cut squares that look like UC14 based on the description given in the Scott Catalog and the description given in "CATALOG OF THE 20TH AND 21ST CENTURY STAMPED ENVELOPES AND WRAPPERS OF THE UNITED STATES Edition 4.3, June 2020." Scott describes the tilt of some of the letters in UNITED STATES as well as the curve of the right wing and the acute angle made by the front of the aircraft and the engine as as way to identify UC14. UPSS describes the rounded tail skid and blunt tail as indicators of UC14. The images below show these characteristics.

However, both Scott and UPSS state that UC14 is 21.5mm and UC15 is 22mm. The images below also show the stamps as being 22mm. I know these are 25 cent stamps, but I do want to properly identify them. Are the measurements in Scott and UPSS accurate? Is there some variability with the actual dimensions? I'm thinking there is and that the stamps below are UC14.

Catalog measurements are accurate for this stamp impression. Measuring the stamp is difficult. I use a magnifier with a graticule in millimeters and it is still tough sometimes.

Remember to check the "T"s as specified in the UPSS catalog for help in identification.

Measurement is best done bye comparison to a known stamp impression. See the tips for measuring the difference between flat bed and rotary stamps for more information.

I agree with jobi01.

I also note that your two images appear to have come from heavily inked strikes, which may have contributed to the measurement difficulties. The outer edge of the design would dribble in the same manner as the interior (image) components, resulting in a slightly longer measurement of the height.