Hornady .444 cases are about .2 shorter. Reloaders already consider them "special" enough to toss them or sell 200 1x fired for $35 shipped (last month on MO).
We know from posts on this forum that accuracy does not suffer when 44SP are shot in a 445 Super Mag chamber, and 38SP are fired in a 357Max chamber. The free-bore the 38SP and 44SP have to deal with is a whopping .450". I see no reason why accuracy would suffer if a 444 Marlin case was 1.775" long, it has to deal with exactly the same amount of free-bore as the 38SP and 44SP. For what it is worth.
It would be great if someone with a 444 Marlin with known accuracy would test this.
