Quote: Can you shoot a .44Mag in a .444 Marlin rifle? If so how about the .44 Special?
Can you, as in, will the gun fire? Probably. The case heads are the same size, both use large primers (rifle/pistol), bullets are the same diameter-- some use .44 Mag bullets in the .444.
Probably not a very good idea, though. The .444 is significantly longer than the .44 Mag, which isn't of itself that big a deal -- there are guns designed to shoot .410 shotshells and .45 Colts in the same barrels. But it can affect accuracy.
What would make me nervous about doing it is the body taper built into the .444 that isn't in the .44 Mag. The .44 Magnum has no body taper. The .444 body is between .015 and .020 wider by the case head: it tapers from .470 by the case head to .453 at the case mouth. The .44 Magnum body is .452 or .456 (depending on your reference book), so when you fire it in a .444 chamber, what will happen by the case head? The web will have to stretch out to make a seal in the chamber, if it has enough elasticity to do so. So, it will stretch and make the seal or it will fail in the attempt. I don't like either potential result, personally, because you can't predict what each lot of cases will do from different manufacturers, how hard they are, how thick the webs actually are from different manufacturers.
Here's something else to consider: How wide is the chamber where the .44 Magnum case mouth ends in it? It is .94 inch shorter than the .444 chamber, and the .444 has, as I have told you, a body taper. So it's wider there than at its mouth. Depending on how thick the case really is, and how wide the chamber really is (I'm talking about manufacturing differences), you could have case splits.
So, altogether, it doesn't sound like something I would want to be holding next to my face when it goes off.
Your mileage may vary, of course.