Having worked for many years in aviation makes me a sort of rivet conniseur The pull shank is one of the most determinant features of a (blind) rivet. Besides the body material, there are many different types of steel shanks offered from mild to very high alloy to stainless alloys, depending on the compressive force needed. The tensile strength of the shank determines how hard the rivet compresses.

There are even special types of 'rivets' like Hi-locks and Jo-Bolts where the shank is very strong; so strong that a normal puller just won't cut it.

http://www.tpub.com/air/2-4.htm

Also a big puller limits where you can use such a rivet since you must allow clearance for the pull tool to install it. So the center shank is threaded and a special collared nut is threaded and tightened onto the shank to the point of breaking the shank in tension thereby extruding the rivet body; the same thing a rivet puller does, and all you need is a wrench. Despite the presence of threads, these are really rivets.

jimbo