For smaller than .280I would suggest 250 savage 257 roberts or a 25-35 in winchester 94. These are smaller (meaning in bullet diameter.) They also have less recoil. A .243 is smaller than the 280 and also has less recoil, but does have better capabilities than the 100 yard rangeor less that you seem to be looking for.

Even the 250 savage and 257 roberts will be lethal on whitetails beyond 100 yards.

Were you asking for a caliber thats maximum effective range was 100 yards or less and that is smaller than .280?

Thereare very few rifles that fit that billand are smaller than .280.
The 25-35 , and 25-20 are about the only thatI can think of that would (ONLY) be effective inside 100 yards and. And I honestly wouldn't use the 25-20. My choice would be the 25-35 and even that is still effective beyond 100 yds.

There are a few in the larger calibers that are good (inside) 100 yds. they are the 44 mag, 357, 32-20, 32-40, 38-40, 38-55. And in my opinion, I would only use about 3 of these rounds for deer inside 100 yds. And also good luck finding some of these cartridges and the guns that fire them. You can find them , but some might cost an arm and a leg.

If you want less recoil,I would go with what alot of the other members are recommending. .243,.244 rem, 6mm, 250 savage, 257 roberts, 25-35, 25-06, 6.5mm, 7mm-08, 7-30 waters, 300 savage, 30-30.

Most of theseare considered (mild) cartridges, and they have all killed thier fair share of deer. However, They can and will all be effective beyond 100 yds. If I had my choice between the list of sub 100 yd guns and this (mild cartridge list)...... I would choose any of those mentioned on the mild cartridge list over the ones mentioned in the short range list.