Originally Posted by stem
Is an i frame smaller than a j?
Yes, but only in the horizontal cyl frame length and cyl window which is what determines frame size.
I and J frame grip frame size does not vary with frame size and are in fact the same for pre 1953 I and J frames.
With the introduction of the Model of 1953 NEW I and NEW J frames, both I and J frames had their grip frame sizes lengthened 1/8", but again they are the same new length and size. And their cyl frame sizes remained different.