I have several Disc Extremes from 45cal to 50cal The first thing I do Before I even Stoot them is to Float the Barrle And make sure that the stock is not touching the barrle but just at the barrle lug. I will sand the inside of the stock or use a thin shim to ftoat . You want to be able to slide a dollor bill between stock & barrle all the way to the lug if you can do this then you are ready to start working up some loads !
A great load in my Extreme is 95gr 2fg loose 777 & a 250gr & 290gr Spitfire TMZ But Very Expensive bullets
Another super load is a 44cal. .430 300gr Xtp & .45cal .452 300gr Gold Dot with same powder charge
With these bullets & powder charges I was Able to shoot 1" shot groups at 100yds