The slower rate of twist only really begins to become a problem when you start using 300gr. plus bullets. It really is more of an issue of length than weight. Over 300gr. and the bullets end up too long for the 1-38 rifling to stabilize sufficiently. The 300gr. Hornady XTC are not as long as many hard cast bullets and work quite well in my 1894P.

Much of the twist rate concerns come from those wishing to push the performance envelope of the round. I prefer to use a rifle cartridge for distances much over 100 yards. I don't view the 44Mag as a great long range hunting round. For my purposes, the lever action can't really replace a serious bolt action for long distance shooting.

The owner of Buffalo Bore made a big deal about the twist rate in something of a rant he posted to his site:

"Marlin (for an unknown, not well thought out reason) is using a very slow rate of twist (1/38 inches) on their 1894 chambered in 44 mag. Because of this slow rate of twist, the heaviest bullet that the factory Marlin will stabilize is about 270grs. Other firearm makers that chamber for the 44 mag all use a much faster rate of twist so that their guns will stabilize and therefore accurately shoot bullets over 300grs. Many folks today want their 44 magnums to be able to utilize the heavy 300gr. and heavier bullets - Marlin has not figured this out. If you want decent accuracy out of our new +p+ load in a Marlin, it will need to be re-barreled with a twist rate of roughly 1/20 inch. I have Dave Clay re-barrel all my Marlin 1894's with a faster twist barrel. A 44 magnum that wont accurately shoot 300gr. or heavier bullets is useless to me."