Hi JBW,
On which page do you find the 2 terms "large" & "small" frame ? I can only guess the "large" frame refers to the guns with removable magazines, and the "small" frame refers to guns with fixed magazines ?
The Long extractor refers to guns serial numbered from 1 to 39,000 (approximately), these guns have the first type of extractor which is 1 1/2" long - the extractor is a flat piece of metal which is usually blued and is located at the top front end of the bolt.
The short extractor refers to guns manufactured from serial range 39,000 till the end of production. This type of extractor is 1 1/4" long.
regards,
Broomie