I was using a .30 cal AWC Thundertrap on mine but at 26oz it made it VERY front heavy.
I am now running a SWR Trident 9 on it. I run SS ONLY in this gun, I have a .308 if I want to go supersonic. I did not notice any real sound difference between the two. The Trident is light so the gun balances well.
I am very happy with this set up. I still have a few things to do to it.