I have 2 Thompson center G2 barrels that came in a package deal and I do not either of these calibers. The 6.8 is new in package 23" bull barrel the 204 Ruger has exactly 8 rounds down it. It is 23" bull as well.
The 204 comes with a MGM mount already mounted.
204 barrel and mount TYD $250
6.8 barrel in package TYD $225
pm me for pics and I can text them or email them.