The length of a shotshell is based on their fired length. Assuming both shells are nominally 2 3/4" long then a loaded Roll Crimp shell will be longer than a loaded fold crimp shell. Depending upon your viewpoint the roll crimp shell either requires or allows a longer wad column. The old roll crimp 2 5/8" shell had approximately the same loaded length as a 2 3/4" fold crimp shell thus about the same internal capacity. Most hulls will not measure exactly what their nominal length calls for, quite often running a bit short.
