i disagree with the 243 for several reasons. now , on game , this is a great all around cart, but for primarily target shooting your are should be good out to 300 yds easy, if you wanna do some longer range work, i would suggest 3 , my personal fave the old 6mm remmy , the 308, and the 6.5 swede. the 308 and the 6.5 swede you can get excellent quality milsurp or new mfgr rounds for both. the 6mm and the 6.5 are noted for shooting like a lazer throuhg the wind and not moving. the 6mm , you can still get new mfgr rounds at academy for about 8 to 10 bucks a box. also the 6mm case design is much better and longer lasting on the throat/neck/ chamber of a rifle than a 243, the 243 is very unstable in this regard.
i would get a rifle that makes you be a better shot, that you have to work for it.
go find an old remmy mohawk, or 788, with a upper vent rib, 16 in bbl, and fully adjustable rear site, in 6mm, you can get them at gun shows for about 3 to 500 bucks, depending on condition. they are a great, light, handy rifle.