I have been thinking of a 375 something for over a year now. This is one of the better ideas I have seen. It will fucntion easily through a bolt action and you could even shorten 458 Win Mag brass to get to where you are going. The best version of what you describe is the old 38-56 AI. The 38-56 Win. was simply a 45-70 case necked down to 375/38. It was chambered in the 1886 and this was a converstion tha offered a decent improvemnet over the orignal case. The draw back to the 45-70 in a blot is gun is a large bolt face and gettin' it to feed. I had not considered either the 450 case or shortening the the 458 case for this task prior to your thread, but it should work well. In the end you are going to a 300 grain bullet at about 2000 fps maybe 2200 at the outside. Not a lot of difference from the 375-06 and that is a bit more common for both reamers and dies, something to consider int he cost of a wildcat. Besides, the 375-0 will function in the same action as your 375-450 and be easier on your wallet as well. 30-60 brass is cheap, readily available and lots of folks just throw it away.
