There are several quality "rifled-slug" ammo out there. These are deadly on dere sized game and accurate in mostsmooth bores out to about 75-100 yards or so. Main problem some folks seem to have, me included, is managing the drop. It is rather dramatic because the friction of the air passing over the bullet's "rifling" , which is what causes the bullet to spin so that it remains on line,eats up energy that would other wise have been retained in the velocity of the bullet.(It is a Newtonian physics conservation of energy thing.) But with practice at the range, managing this isrelativley easy to learn.

Of the choices you mentioned - In this order: (1) 270 Win. (2) 243 Win. (3) 30/30 Win. Certainly all are adequate for deer sized game. From my expereince, the 130 gr. bullets is about optimum for the 270 Win., 100 gr. for the 243 Win., and 150 gr. for the 30/30 WIn. If you go with the 30/30 Win., be sure to try the new Hornady polymer tipped ammo developed for tube fed lever actions.It is substantially more expensive than most flat nose ammo, but there is a real gain in ballistic performance,i.e the arc is substantially reduced because the velocity is retained better .... it is flatter shooting.