.Oskar;
No problem; I wondered why you came back with an identical posting after my post. I have seen some posts come up like that before with no apparent reason, just a glitch in the system I guess. You are correct as to when the 3" Magnum using a heavier payload at higher velocity was introduced. Both longer chambers & shells/hulls had been available to order for quite some time prior to that though.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra