Only the first inch of a 444 is the same size as a 44. It rattles around a lot in the 444 chamber but closes ok. I did not fire one.
After firing in a 444, your 44 brass would not chamber in a 44 again and may not fit back in a 44 sizing die. Full 44 loads may not survive for long. I would just load reduced loads in the 444 for practice, as accuracy would not be good in the long chamber with the 44s, similar to a 45 in the 410.