You are not going to get great accuracy shooting FMJ ammo.
Here is an example shooting some factory varmint ammo (50 grain Federal) from an HBAR profile 8 twist 16" barrel. This was earlier this month over some bags. This is three, 3 shot groups. Average into the .3s. I would expect that at 200 yards I would still be around the 1" range + or - a couple tenths.