Patriot Issues

I own a number of Mossberg rifles and shotguns.
Around 2 years ago I purchased a Patriot in .338 Win Mag.
It can’t hit the broad side of a barn from the inside shooting out.
I’m looking for suggestions.
So far I have done the following:
1. Tightened or replaced the scope, base, and rings (three times)
2. Installed a muzzle brake hoping to change the barrel harmonics.
3. Tightened and loctite stock action screws.

Out of curiosity, have you bore sighted the scope? What type of scope is it? Have you tried different ammunition(different grains)? My 308 patriot absolutely does not like anything other than 165gr bullets. The only time I had issues like you’re having was prior to having my scope bore sighted correctly. Since then, I’m minute of deer out to 300 yards with ease.