Some of the uppers you can get are 204, 223, 6.5, 6.8, 308 the Rugers, and on and on. Different barrel configurations, stocks. Its like a multi round Contender or Encore.
Some of those uppers you need an AR10 lower, like the 308, 260 and so forth because of cartridge length, but yes they are very versital. How dare you though, compare the AR platformto a TC, thats just not right!