I too have been a fan of 44 caliber rifles and handguns for some time. Those that think a properly loaded .44 Mag. is not a fine game rifle, just have not used it. Both my Marlin 1894P and Ruger Mod. 77/44 has put down hogs and deer, plus some "River Pests"! However, its case capacity id designed around powder burning rates for handguns.
It works in a rifle barrel, but never reaches its full potential. By increasing the case capacity to 35/37 grs of medium/fast burn powders (IMR 3031, Re7, and maybe IMR 4198), we see a marked improvement. With these powders combined with a 265 gr hard cast or jacketed bullet, we have a real powerhouse in a small package. With these powders I think 18" is as short as the barrel should be. The overall length of the cartridge, about as long as a .30-30 Win, makes an ideal conversion for any rifle designed for that cartridge. The major improvement this cartridge gives over the .44 mag is with bullets 265 grs and up.
Yes, the Ruger .44 auto was, and is, a fine little brush gun. Accuracy has been improved with factory offerings at .430" (jacketed) instead of the old .429".....and with hard cast (21/24 bhn) sized at .431". This hard bullets, with gas checks, do not lead up the gas system. No, the .44 Mag. Max. is just too long for the Ruger auto action.
There has been quite a bit of engineering gone into the specs of the .44 Mag. Max. We will just have to see if it takes off in the present market or not.
We are now waiting on the reamers to be finished. Two rifles are in the works now. A short handy Marlin 336 and a heavy barrel Rem. 788. The 788 will be used for accuracy and load development.
Keep in touch and Best Regards To All......James