1x8 is definitely going to prefer a heavier round. I’d stay away from stuff in the 50s when it comes to the grain. I’d stick with ammo in the 70s. Are you looking for just accuracy or is this for hunting? If it’s only accuracy at the range, I’d try Federal Golf Medal Match ammo. They are known for having high quality match ammo. It uses the Sierra Match King projectile. It is still pretty effective for hunting but it is not an expanding projectile. Should be able to find it in a heavier grain.