There is no problem with most bullets for deer in a .50. The problem is usually with the shooter, powder, primers and equipment. You will have to test out several and see which works best. I would not go shoot 3 the week before season starts and expect it to work fine the day of the hunt.
I use a .451 250 grain Hornady XTP which worked quite well on my deer last year. There should be no problem with the Federal bullet, however I would check the minimum expansion velocity, and match that to the powder you plan to use. You will also have to chrono your loads if you expect to be shooting at longer than normal muzzle loader ranges. I imagine, even with the new powders, beyond 200 yards the velocities will start to drop off too much and you won't be able to get good expansion, which may or may not pose a problem.
I had problems for several years, and it was the sights. I could not get anything to work right, and trying to find a good set of sights was a pain. I not have a Williams peep on my inline and have had no issues since then.