No particular reason and maybe not even a practical stretch "what if" reason other than it seemed the most universal of that category of 45 cal cartridges that would fit in the Montana 99 action I had. And IIRC it has some history in Africa dating back into the early 1950s. I think Jack O. used one for DG in Africa. In fact it was never promoted and probably came before its time. The Lott was later promoted, became a standardized cartridge and filled that niche. If needed, both the 458 WM and 458 Lott can both be shot in the Watts without issue. The next longer 45 cal basic belted mag would be the 458 Express which, IMO, seems a tad too long and really limits the COAL options with some bullets. But a nice thing about these basic belted mag cases is if they are a little too long with some bullets, you can simply trim them shorter, seat the bullet and go- within reason of course. And, no way of knowing for sure but I can use practically all published Lott data, no matter the bullet or powder, without any pressure issue. Don't know if it is my particular chamber, throat specs or bore but sure seems that way. Nice to not have to worry about potential pressure problems.
And yes, as Opposite Pole pointed out, annealing cases can really extend their useful lifespan if you take care in the annealing and resize correctly. The secret to annealing is knowing the best temp range and area of case to anneal and procedure to do it correctly. I've done it for years on quite a few large cases without issue and some of them, like one batch 45-70s used for low pressure loads, have countless firings, certainly north of 40 or 50. The theory is to soften the neck/shoulder area just enough so it doesn't split because of work hardening and to not soften the body where it needs to remain hard. Here's an annealed 450 Watts. Also, I think the annealing "colors" show on new Lapua cases as they anneal as a last or near last step in their process and don't polish away the annealing color hues.
