NO ONE is willing to do anything that may make an advertiser angry, like write a bad review of the product.
EVERYONE will alter the results of a shooting test to make a big advertisers gun look good.
I know a guy who's been a gunwriter for thirty years, and he will not write a bad review, but not for misrepresenting the gun; poorly performing guns are returned, and the manufacturer given a chance to fix them.
If the gun is fixed, either through repair or further development, and performs well, the need for repair is disclosed in the subsequent article.
So, yeah, you're unlikely to see a bad review in print, but not because the writer is lying about the gun's performance.