Are the loading tubes necessary??? Of course not. I hunted 20 years without them. Are they handy for hunting... absolutely. Carry five pre measured loads and a loaded rifle and your good for all day.

In your .50 caliber I would get some Pyrodex RS in loose form. I would load 90 grains of that and a 250 grain Shockwave and see how that shoots. Another good bullet would be some of the XTP's out there in packs. Be sure to swab between shots and you should be doing real well.