Seen a few threads of people spitballing when I googled, but not much on anyone actually trying something like this. Closest I saw was .44 BGM, which used a 45mm case. Figure before I go naming this one (which I do intend to use in the next project rifle after my .357 Mag project, and have made a dummy of), I should ask and make sure that a roughly 10.9x51 wildcat doesn’t already exist.
Search Google for "44-308 wildcat".
Did that, again I saw lots of spitballing but not much outside of .44 BGM for “things folks have actually tried”, unless I’m missing some big thread. I’m looking to go with a case that’s halfway between the BGM and a rimless .444 Marlin to keep the brass making easier
I'm in the process of building a .444 rimless. Cartridge will be same length as the 444 Marlin to simplify dies.
There's a guy on ARFCOM that made an AR-15 upper that fires a long 44 Auto Mag. I don't recall the case length, but obviously the COAL was just under 2.260" to fit in the magazine.
Tony