My rifle is rated for 120 grns of black powder. Like said above, not all powders are the same. I can't throw 120 grns of 777fffg in it and still have it be safe. It might take it, but I don't want to be the one to find out.

I have found that mine shoots best with 95-100 grn of pyrodex, 105-110 grns of clean shot and around 90 grns of 777.

And with the proper bullets mine is plenty flat enough and has more than enough energy to do what I wan't with it.

I think the magnum charges work well with heavier bullets, but some may have problems with large charges and lighter bullets looking for the most speed they can get. I think you can reach a point where the bullet is just too fast for the barrel. I have the same problem with my slug gun. If I try to shoot the new slugs that are faster than 1700 or 1800 fps my accuracy at 100 yards just isn't there. At least not with the bullets that are currently on the market.

Not every rifle is the same though, so sometimes you can make it work, other times maybe not, or it may be very difficult to find the right combo. Some times a longer heavier bullet might help, or a different sabot. Bullet design is a big part of accuracy sometimes.

Paul