Lamar--the 44/40 case has more capacity than does the 44 Magnum--at least a full grain more of RL-7, maybe more with the R-P and W-W cases. The 44/40 would have even more yet than a shorter 44 Special.
I had this idea a few years back when I was messing around with the late John Kort's idea of using 100%-density loads of RL-7 in the hyphenated Winchester rounds like 32/20 and 44/40. This was more about giving bullet-base support to castings like Lyman #311008 and #427098, which lack a crimp groove to secure the bullet against telescoping while the cartridges shunt down the mag tube in leverguns. When 008 and 098 were new, black powder was the only fuel available, and the BP column supported the bullet in similat fashion. A crimp was set around the bullet ogive, and made for a solid, stable package. RL-7 worked perfectly in this manner for both 32/20 and 44/40, giving ~1125-1150 FPS and not much bore debris in rifles; it was a little dirtier in 4-3/4" revolver barrels, but still not bad.
Never able to LEAVE WELL-ENOUGH ALONE, I tried 100%-density loads of RL-7 in 357 and 44 Magnum loads using a couple bullet weights with each caliber. They worked, they were accurate enough, and left a bit of bore grit/zombies after each shot, but like the 32/20 and 44/40 velocities were quite moderate, about 1100 FPS again. Mid-level weights of Unique or Herco use about 35% the powder weight to get the same perfornamce level. Whatever money you might be saving via absence of gas checks would be lost to powder cost per round of almost 3X per shot. In short, RL-7 works OK in this application--but there are more cost-effective ways to go about this business of moderate-power loads for Magnum revolver calibers. I suspect that after 3-5 cylinder-fulls of these RL-7 loads in a swing-out or top-break revolver, that powder grit would play h--l with extractor clearances and cause stoppages.
