So I am looking to get into the AR family. I want options seeing I have small children who love to hunt already. I would like to purchase an AR 10 possibly that would allow me the options of having a 243,7/08, 6.5 creedmoor, 308, and 260. I would like to end up with 2 maybe 3 of theses calibers. To best of my knowledge all the mentioned use the same 7.62x51 bolt. So could I use same lower and upper and just change barrels when swapping calibers. Or would I need to have separate upper and barrel combos to switch out. Thanks for your help in advance. Any information is greatly appreciated.