For under 100 yards, the 30-30 has more than enough knock down power for any deer alive. I have a friend that hunts elk exclusively with a 30-30. He just keeps his shots to under 150 yards.

If you really have your heart set on something "new", I would recommend a 270 or 30-06. They do have better trajectory, although for shots less than 100 yards that really isn't a factor either.

How about going with a blackpowder? A 50 caliber would be a good choice.

Good luck