That is only a little more than the difference that I got between reloads equivalent to factory loaded 246 grain .44 Specials and standard 240 grain Magnums with my first S&W .44 Magnum, an 8 3/8" Model 29-2. My groups were a foot apart vertically at 25 yards. The reason is that Special bullets are in the recoiling barrel approximately twice as long. The muzzle rises more before they exit. It varies with how you hold the revolver.

While they are not good looking, for me the rubber Hogue Mono-grips are the most comfortable on S&W .44 Magnums. They are only about $22 at full retail which is not to big a gamble. I often see used ones for sale for less.