I think that a little more info is in order....are your groups from a bench rest set-up or are they standing off-hand, for example? If they're a bench, then they suck. If they're off-hand, well, you're not doing too shabby..
1. Try different powder charges, granulations, and types. Some guns like it hot, some don't (I'd put yours here, it seems, from your info). Pyrodex shoots better in some guns than 777 does. Some guns like pellets better than loose. Etc.
2. You need to buy several different types of bullets to try. Two isn't enough to figure out what it likes. Honestly, try the different T/C bullets first, they are the ones that the gun is designed to shoot.
3. Try a different primer.
4. Try a different scope. Scopes are mechanical and can/will fail at any time.
5. Make sure that the stock bolts are tight.
6. What type of shooting bench set-up are shooting from?
I had a blue/syn Omega (now called the Z5) and it shot 3/4" right out of the box with 100gr of 777 FFFg and the 250gr Shockwave. Didn't even try anything else in it, I figured I was good. I now have a stainless/syn one that groups under an inch with 100gr of 777 FFg and the 250g gr SW. It shoots the Mag Express 300gr and the 300gr SW almost as well with 100gr of 777 FFg. I have NOT had good results with the 200gr SW as of yet, but it's going to get another try.
It took a bit of shooting for this gun to settle in, unlike the blued one. After the 50 round mark, groupsw became much more consistent and tightened up a good bit as well.
I have found that in most of my guns, I got better accuracy with FFFg 777 than with FFg, but I bought 5 cans of the FFg on clearance for $10 a can this spring, so that's what I'm shooting right now.
In the stainless gun, for 777 primers are worthless, for some reason. I had consistent misfires with them, bought another pack at a different store, and the same problem. The blued one loved the 777 primers. I switched to the Remington Kleen-bore primer for the stainless gun and haven't had any problems.
The stock could be the problem..... It could also be that the crown of the barrel past the QLA is not concentric or is damaged... The only way to find out if that's the problem is to either take it to a gunsmith or send it back to T/C.