What is wrong with .444 brass? Rimmed? Don't let that bother you. Rimmed is actually not that difficult with single-stack mags and a barrel breech that is contoured like a PSL to mate with the bolt. Get a PSL bolt/bolt carrier combo from TN guns and go to it.
I doubt it, because the .444 is a slightly tapered round. You'd have to have a tapered reamer to match.this is likely going to require a special reamer. I have been wondering if a standard reamer and using longer brass would work possably.
Ditto for dies.
Now another thought - the Handloader's Manual of Cartridge Conversions (HMCC) indicates there is a .44/06 cartridge, which is *EXACTLY* what it sounds like - 30.06 brass necked out for a .44 round. The description suggests a .44 mag die set could be used. Something to think about! Case length = 1.285. A little shorter than the .44 Automag but you get the idea.
Another off the wall idea is to look at those magnum rounds like the .458 Winchester, .300 Remington Ultra Mag, etc. and see what you can get with them. Remove the belt, neck up/down, and presto a rimless cartridge with higher capacity than the .444, meaning even better performance. The advantage to doing something like that is that it will perform better, and you could rebate the rim like on a .50 Beowulf. If you are going to remove the rim on .444 brass, you may as well go all out! Rebate it down to 7.62x54R size and use a Yugo/RPK trunion + PSL bolt combo like I'm doing. That will enable you up to 50,000 CUP pressures.
Mate that with a .30-06 BAR or 8mm magazine, and you'll have a 15-round
Did you know that most die sets have a crimping function built into them? At least Hornady and RCBS dies have it. You have to tweak the body of the bullet seating die so that it touches the end of the brass, THEN you adjust the bullet seating cup down into that, so it seats the bullet inside the brass, then crimps it at the end of the stroke. Trial-and-error to get right, but it can save you some effort with the Lee stuff. I have the Lee stuff and use it, but I'm going to start testing the built-in crimping capability.I suspect that I may have to crimp to keep the bullets in place under recoil. The lee factory crimp die is cheap and does not do a role crimp but more of a multi demple crimp like you see on factory commercial ammo. I think this will work well because it still leaves a sharp edge at the case mouth that is needed for more sure head spacing.