I have a Ruger Blackhawk in .44 Mag that I would like to start loading cast bullets for so that I can enjoy a little more trigger time for a little less money. I have no idea what is fact and what is fiction in this area, but some of the things I have heard revolve around the hardness of the bullet and the speed at which it is going and how it can have detrimental effects from the amount of lead fouling produced.

Thanks in advance for the clarity.

Forget all the stuff you read and shoot lead! I use .431 to .432 boolits, Felix lube or Carnauba Red. I use 320 to 330 gr boolits, LBT style with 21.5 gr's of 296 and the Fed 150 primer. I have reached several 1" groups at 100 yd's and average around 1" and under at 50 yd's.
Brass consistancy will be more important then the boolit for accuracy.
Water dropped WW metal is good but I do make mine a little harder for hunting by adding a small amount of tin and antimony.
50-50 WW and pure, water dropped, also shoots good so you see, there is a lot of latitude.
I have shot thousands of rounds for months without cleaning and the small amount of lead is the same as it is after 6 shots.
If you don't cast, choose your boolits carefully. Stay away from the super hard junk boolits with bevel bases. Beartooth, LBT, Cast Performance, etc are the best.

Most important factor in preventing a leaded mess is good bullet fit. The throats of the cylinder should be slightly larger than the groove diameter of the bore, and the bullets should be a good snug fit. Some Rugers have somewhat oversized throats and the common .429" or .430" bullets are loose in them. That leads to leakage of hot gas around them that causes leading. Even worse with a revolver is if you have throats smaller than the groove diameter of the bore so that you can't shoot bullets big enough to fill the bore. You get leakage all the way down the bore, and bad leading. In that case you have to get the throats reamed or honed out to get decent results with lead bullets. Sometimes having the alloy a bit soft will help with this problem by letting the bullets set back and obturate under pressure to fill the bore.

My 7 1/2" Super Blackhawk with .430" groove barrel and .431" chamber throats will shoot very soft plain based 240 grain bullets at 1575 FPS over a full load of W296, with minimal leading. But I've gotten horrible messes in it shooting Speer .429" swaged lead bullets at only 1000 FPS with 2400. (2400 burns hotter than 296, which is another factor.) Undersized bullet leaking gas, lubed with a thin coat of dry wax like a .22, low pressure that doesn't make the bullet obturate, and hot gas from a hot burning powder = leading. Those bullets do great with milder .44 Special loads, and aren't bad with full loads of 296 and similar Ball powders.

I don't buy swaged or cast bullets anymore since I got into casting my own, of course. That's a great hobby in itself. Wish I didn't have to work for a living so I had enough time for it!