Jack said he "invented" the .450 Lott because if you fired .458 Win Mag in a .450 Watt's (which was already known), the end of the chamber would shave jacket material off the side of the bullet as it entered the chamber.
Lott wrote it up that way.
The Lott chamber, in which the body was about identical to the .450 Watt's, except there was no "mean little" shoulder at the end of the ctg. cut tout, just a smooth ramp up into the throat.
Now, if that is done on commercial rifles chambered for the Lott, I don't know, but that is how the original .450 Lott's reamer was ground.
I shot a factory chambered .450 Watts, pre-64 Model 70 Winchester back in about the spring of 1973. That was at Les Hatfield's back yard, just off Highway 16 West, on Walcott road, B.C. Quite a ctg.