I had an unauthentic copy of the Colt 1851 Navy in .44 caliber many years ago. The most I could get into it was about 30 grains. The cylinder is smaller than the other .44 calibers and each chamber won't hold as much.
Perhaps there are .44 caliber 1851 out there that will hold 40 grains, but I've never seen or heard of one.
Brass-framed revolvers are not able to withstand the higher pressures as well as their steel-framed counterparts. So, don't load maximum loads in it as a steady practice.
Check your game laws before you hunt deer with that revolver. A minimum power level may be required for deer. Your revolver may not reach that level.