To me, a Colt with a collet bushing and no internal firing pin safety is a "Series 70."
Well, it IS, says so right on the gun. Unless it is one of the few hundred "BB" (Barrel and Bushing, not Daisy) guns made before they changed to the "Mk IV Series 70" rollmark.
There is a legend that Mk IV is to honor one of the design team named Mark Ivey. Right.
I think it is the fourth variation; counting the base Government Model as Mk I, but not so named because at the time they could not conceive of monkeying with the design.
I THINK the Mk II was the second variant of the .38 Wadcutter Gold Cup.
I know the Mk III was the last variant of the .38 Wadcutter Gold Cup.
(It was also the coil spring Trooper Mk III family of 1969, apparently the automatic and revolver departments were not on speaking terms.)
I think the Series II Kimber without a Series I is like Colt without a Mk I. They thought they were doing OK and had no reason to mark a gun One when there was no plan for a Two at the time.
Better attitude than those ambitious promoters who announce the First Annual Concert or a new author's "first book in a trilogy."