No. No change that I know of, though you could call Accurate and double-check that if you want to. There is normal lot variance of course. #5 is a faster powder than the higher numbers, so it just isn't able to achieve as much velocity in same-pressure loads. Larger charges of slow powders that reach the same peak pressure keep the pressure up longer. I think that in the abbreviated PDF file manuals you download online, they're just figuring not enough folks want to load a magnum down to use up their limited space with reduced .44 Mag loads.
Lots of us like to put some target plinker loads into .44 Mag brass for maximum accuracy. Lead bullets and a case full of Trail Boss is great for that. And here's a good approach to reduced loads: Note that the maximum COL for .44 Magnum (1.610") and .44 Special (1.615") are virtually the same (well, 0.005" different, but that's not significant to pressure). That's because the .44 Magnum was developed by Elmer Keith in .44 Special cases in heavy revolvers. The .44 Magnum case is longer only to prevent the higher pressure magnum loads from accidentally being chambered and fired in a light .44 Special revolver. So, it turns out that any load you find for .44 Special will give you essentially the same pressure in a .44 Magnum case as long as you use the same COL. Some .44 Mag brass is slightly heavier in the head area, but the .44 Magnum gun won't care about the rise in pressure that causes, as it will still be well below magnum pressures.
If a crimp groove or cannelure you want to use prevents you from using the same COL as the .44 Special, the pressure will be lower with a longer COL in the .44 Magnum case. You have to be careful the longer round doesn't protrude from the end of the chamber, but if your cylinder is long enough it will let you do this. You can raise the charge around 10% to get similar performance in the larger volume under the bullet that this seating difference creates. The easiest way to do this is with a chronograph. You can put the load in a few .44 Special cases to see what the velocity is, then adjust the load up in the magnum case to get a velocity match to the .44 Special readings. That is safe to do as the case gets bigger. The reverse is not true as it takes more pressure in a smaller volume to get equal velocity from the same bullet and powder.
Meanwhile, if you want to load to magnum pressures with #5 or even with #2 or Nitro 100, there is nothing to stop you. The charge weights get smaller as the powder gets faster and the case fill gets poorer and the velocity you get from the same maximum pressure goes down because the lighter charges have less total chemical energy available to put into the bullet, but there are times when that's fine.
If you have modern #5 on hand, knock the recommended charges down 10% work up to allow for lot differences, and, as I said, you can double-check with Accurate. My old Accurate manual has all five of those powders listed in .44 Magnum if you need load data for a particular bullet?
