Why not just have a gunsmith re-stamp the barrel .44mag and carry .44mag ammo.
The .444 is just a .44mag lengthened to 2.225".
Yes, the case head in front of the rim on the .444 is 0.018 larger, but until you reload the case, it's just like shooting a .22short in a .22lr chamber.
Accuracy may suffer just a tad due to the longer throat, but velocity over a .44mag will be slightly enhanced (ie: Weatherby free-bore).
And yes!, the standard reply is: "TELL IT TO THE JUDGE !!!"
but if the barrel is professionally restamped to .44mag and you only have .44mag ammo, it likely (original chamber) is unlikely to be questioned. This is of course if the rifle will cycle the .44mag. If not, then you have a single shot rifle.
But, you WILL be checked if the Officer see's the rifle in hand. WE aren't all firearms/ammo dummies...!!!
RE: the original poster was talking of the Stainless Steel XLR w/24"bbl in .444.
If it is a "Marlin" as contrasted to a "Marlington"; it will bring upwards of $1,000 on GunBroker.
I have a "corrected" Marlington .338MXLR and on GB would likely bring over $1,000 (Stainless .338MX w/gray laminate stock; no barrel droop).
Neither it nor my .338MX (blue/walnut circa 2009 w/o droop) are for sale...