First of all, I believe your current 30-30 rifle is more than capable of killing ANY deer that walks the face of the earth within 100yds! This even includes the MONSTER BUCKS, both here in America and Canada!

I guess its better to have the itch for a new rifle as opposed to a new wife hehehe. Since this is case, I will offer the following for what it's worth. Since there are so many calibers that would do the job for you at the marginal distance of 100yds, I will offer only those which have served my friends and I so well over the years.

My favorite short-action calibers are:
1. 308 Winchester (150 or 165gr bullets)
2. 7mm-08 Remington (140-150gr bullets)

My favorite long-action calibers are:
1. 30-06 Spfd. (165, 150, 180gr bullets)
2. 7mm Remington Magnum (150 or 160gr bullets)
3. 280 Remington (140 to 160gr bullets)
4. 270 Winchester (130, 140 or 150gr bullets)

Any of these will do the job especially if you find an accurate load and place the shot in the right spot (I prefer my shot just behind the shoulder).

Isn't great to have so many calibers to choose from and so little time-gee havn't we heard that saying before about women lol.

Remember just like women, if you find "good shooting one" you better hang on to it.

The most important things in life-God, Family, Hunting and Shooting.