WB
I know, me too. "I", "J", "E" Colt frames. S&W I get.
Wednesday, August 22, 2018, 14:07

Besides the Colt frame sizes each one had about three different gripframe designs, long, sort, round, flat...

The Police Positive was the same frame size but a totally different grip frame on the chassis from the Pocket Positive, much longer grip and flat bottomed. The Detective Special is actually the "Police Positive Special (longer frame window and cylinder for the .38 Special) with a shorter flat bottom grip frame. I believe a "D" frame in Colt nomenclature.

I can barely order the correct grips after much research.

The original Police Positive and Pocket Positives were found in .32 Colt (a heeled bullet centerfire round) that has perfectly smooth cylinder chambers straight through. I have reamed out a cylinder or two of .32 Colt to .32 S&W for economy of use. It did few harm and made ammo much easier to find. Too easy to plunk common .32 ACP in there afterward, just point skyward to eject so the brass does not hang under the star. The 32 New Police is simply the .32 S&W. Ditto the .38 Colt New Police and .38 S&W (not the Special).

It is confusing but I guess that's part of the allure. If it was easy anyone could do it.

A useful link to a article of some explanation on frame sizes.
http://www.coltfever.com/Colt_Model_Guide.html