Steve;
Note that the length of a hull is determined by its New/Unloaded/fired length. Thus the type of crimp itself has no bearing on the length of the hull. Once loaded though the fold crimp uses more of the hull in crimping thus has a shorter loaded length than does a hull starting at the same length but roll crimped. In fact a 65mm (2 9/16") roll crimp & A 70mm (2 3/4") fold crimp shell will end up as loaded having very close to the same loaded length. Thus either of these shells will have a bit of clearance between the end of the shell (loaded) & end of chamber. How ever "IF" you take the 2 3/4" hull & roll crimp it the loaded length becomes longer & that chamber clearance is encroached upon.
