Advocate,
You should find that gas checks are really not needed until velocities exceed 1500 fps. That has been kind of a general rule of thumb for many years and, I have found that to be true, for the most part, in my experience. BUT...... bullet strength, diameter and sectional density all have a roll to play, as well as the condition of the barrel, and the burning rate of the powder.
In the .44, I will say that a plain based bullet weighing 250 grains made of 10-12 b.h.n. alloy (wheelweights) using a slow burning powder such as 4227, one should easily attain 1,500 f.p.s. and beyond, in a rifle barrel with no leading or accuracy problems. As the bullet weight increases, so does the pressure to maintain the velocity, and at some point, probably around 20,000-25,000 p.s.i., accuracy will begin to suffer and some leading may start to appear. Then the gas checked bullet would come into it's own.
Sixgun,
Sounds like your alloy may be too hard. Try running a softer alloy. You may find that will help.
w30wcf