There are a lot of 9mm semi auto pistols that have sufficient mechanical accuracy to fit the OP's bill.

It does not have to be a Walther P88, or a costly SIG P210 to get great accuracy, a CZ SP-01, Star 30M, RIA 1911, Beretta 92, and even a Glock with a trigger job and improved sights will fill the niche of an accurate plinker, maybe not always within the $500 limit but close to it.

Besides of the mechanical accuracy a gun has to fit the owner to make use of the accuracy potential and has to have good trigger characteristics, so there are no absolute best handguns, imho, but it is always a personal choice.

I can shoot my Glock 17 with a Vanek trigger and Sevigny sights as accurately as my P210-6 but a whole lot faster with better results.

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