sunchine - use what shoots the best. With a Getz .50, I doubt very much, 70gr. of 2F was a very accurate load at 50 yards of beyond. Of course, this all depends on what your accuracy requirements are. That 70gr. 2fcharge, about equivalent to 60gr.3F, will consistantly hit a 6" circle at 50 yards, but that's nothing to crow about.
If your capability due to not knowing the gun or being new to this game is 3" at 50 yards, and the gun's ability due to it's low powder charge is 5", you will be hard put to shot consistantly under about 10"or so.
790gr. was a litte high - edited