I was just over at yahoo.group NEF Group and after seeing a post by John looking for a survival rifle in .444 Marlin, I got to wondering about the .445 myself...
Then I came across this thread over here!
Consider we like the .44, but want a little more out of it. The .445 is just that, without going all the way up to a .444Marlin.
Consider too, the HandiRifle's twist is 1 in 38" which is rather slow for the heavy bullets we would consider using out of the .444Marlin. SO a .445 makes more sense and using 300 gr bullets and less would be idea.
The main reasons I want a .444 is so that I can use bullets HEAVIER than 300 grain and even the 405's now out!
So I think you are onto something with a .445 rechamber. Now how hard is the brass to find???