This question has been tossed around for many years.  I just returned from a Western Kansas muzzleloader hunt for whitetails.  I hunted with my son-in-law.  I use a Knight Bighorn inline with 85 grains of real 2f bp behind a 300 grain Hornady XTP in a Harvester crush rib sabot.  My son-in-law used a CVA inline with a little puny load of 70 grains of 3f of real bp and the same bullet sabot combo as I.  This was not my first hunt with this combo but it was my sil's first hunt with his.  He shot two deer with his puny load.  He shot his buck at about 20 yds with a complete pass through and the deer down within 30 yds of the shot.  His doe was shot at 101 steps also a complete pass through.  Imagine that!! With only 70 grains of 3f real bp he had a complete pass through destroying the lungs.  Man you could not have wiped the smile off his face for several days.  My buck (nothing to write home about, but it was the last day) was shot at about 75 yds and went down in about 20 yds with a complete pass through hitting both the heart and lung.  On all of our deer the wound channel was as good as it gets.  Except for the huge buck I flat missed by being caught out of position and a bad case of buck fever to boot.  Guess you are never too old to experience that phenomenen   (sp).  That buck sneaked in behind me and caught me in a very difficult to shoot position.  Of course since I missed him he was a booner for sure.  Man it sure whet the appitite to go back next year.  

One thing that the right amount of powder will never cue is a deers ability to catch me at just the wrong time. :-)

I think that your question is the most frustrating for anyone new to the muzzle loader and that is because there is no one answer. I have seen 2 people with the same muzzleloader have different expereinces. It is sure different than going and buying a cartridge for your rifle. It also can be influenced by the persons desire to shoulder a larger load of powder. But as your son-in-law proved, most of us have no need to load much more than 70 or 80 grains.

For me it is 80 grains of Pyrodex and a home poured minie ball. I've done as well with a PowerBelt, but those cost money and my friend will supply me with minie balls if i get him lead (BTW - I owe him lead).

Aw!  Come on man!  Everyone knows that that may have worked for Davy Crocket but today's deer require 300+ grs of black powder substitutes ignited by 209 Nuclear primers and tungsten carbide expander slugs to be ethically harvested.    Doubt me?  Just ask the professionals that write in our and other hunting rags.

Last year I got a complete broadside pass-through at about 30 yds on a nice buck with a .490" patched round ball pushed by a "puny" 60 grs FFFg charge.  The ball could was plainly heard bouncing through branches a good 50 yds behind him as well.  I learned of the penetrating power of that .490" ball the first day I shot a muzzleloader.  Got the gun for Christmas and a couple of months later took it shooting and started the learning process.  After sighting it in ad realizing it was a lot more accurate than I'd been told for years a front-stuffer could be, I stacked up a couple of tightly-bound and throughly soaked phone books measuring about 3" thick each and backed off abt 20 pace and shot it hoping to catch the ball.  Nope, plowed right through.  Stacked up more books and fired.  Again, plowed right through.  Stacked all of my books, 7 of them in a line and fired again.  I saw dust kick up several feet behind the stack as the last book fell over.  Already knowing the result I looked anyway and yep, that poky little ball as the experts often describe it had bored nearly straight through about 20"-25" of tightly bound and soaked phone books and kept on trucking.  This was from my CVA St. Louis Hawken cap-lock using the supplied CVA #11 cap igniting a "monster" charge of 90 grs of RS Pyrodex.  No magnum load by any means.  Over the years I learned that my guns and I shoot better with lighter charges and the deer have not seemed to notice the difference.

PA Ridge Runner... first off, congratulations on the deer. Never a bad deer. Only better eating. I always think of the time My Dad shot a HUGE dark black buck. He was so proud!! It was an old swamp buck as they were hunting back marshes that year. He brought it home and mother tried to cook it. The stink drove us out of the house. He finally had to get it processed into sausage and deer sticks. Then he complained about the processing bill for weeks. Sure was not like those corn and soy bean fed ones we normally hunted around the house. They were like prime beef. So congratualtions on a good eating deer.

I remember when you told me of getting that Bighorn rifle. I knew you purchased a great rifle. And without a doubt the Bighorn and Knight rifles in general are a shooter. But for some reason people think they have to burn the new wiz bang powder in 120 grain amounts. When I started with a muzzlelaoder, the standard load was 70 grains of Goes 2f (all we could get) and a .530 patched ball. And I shot a lot of deer with that load. No one mentioned it was under powered. ButI never recovered a single ball from a deer. Always got a pass through. Then the powder craz started and I went along with it. 90 grains and the same ball shot through one deer and killed a second one behind it. I did recover that ball, on the far side of the second deer under the skin.

Sometime for fun, try shooting roundball out of that Bighorn with about 70 grains of 2f powder. It might really surprise you. My Knight LK-II and LK-93 do a great job with roundball, even with a fast twist barrel.

The truth be told I have been trying to get my son-in-law to try a lighter load for several years. Although he is not a really big man stature wise he has always felt that the bigger the better was the way to go. His first muzzleloader was a 58 caliber and a fistful of powder. I do believe that as of now he just may be a convert to less powder can be not only pleasant to shoot but will knock down a deer too.