I use the 295gn copper clad hollow point Powerbelts with 2-50 grn Pyrodex pellets in my 700ML Remington. I really like the way they shoot. I have now shot 5 deer with this combo, and I like the results. All shots have completely passed through, except from one front-on shot. That bullet was recovered just in front of the hindquarters, and the bullet was equal to the diameter of a quarter.
Of the other 4 deer, only one bullet appeared to not expand before exiting. That shot missed ribs on both the entry, and the exit.
Of the 5 deer that I have shot with this load, 3 dropped right where shot, 1 went 10 yards, and the 5th went 30 yards. For me, thats pretty darn good. I am able to shoot 1" groups at 100 yards with this load.

For what its worth, a buddy of mine tried the Barnes expanders with 2-50grn pellets, and didnt use them again after shooting the first deer with them. His results were the same as yours, no expansion, and the deer went about 75 yards on a double lung shot.

My money will stick with the PowerBelts in my 700ML, I've had excellent results with them.