Right on with the 296 Lee!! If a 44 mag wont shoot with 296, there is something wrong with the gun! LOL!........Tell; I drive a 325 grain cast, properly sized, Gas Check bullet out of my modified Marlin 444 (16 1/2" barrel) at 2200 fps. There is no leading, and accuracy is of benchrest quality. A levergun can be made to shoot...and, it can be made to shoot cast bullets at high velocity...but, there are many things that need to be done to achieve that end...not only on the reloading side of it, but to the gun as well. Your 1 1/2" group at 100 yards is good for an unmodified Marlin, but, that same gun with a little work, and the reloading tips I have stated so far will shoot one ragged hole...Is it necessary or practical? That is left up to the shooter.