They may have been refinished, but they sure look like factory N frame square butt Combat grips to me. Aftermarket manufacturers don't install S&W medallions with circle inserts.
Here are a few different factory Combat stocks.
N Sq.
K Sq.
Combat stocks were also produced for round butt grip frames. These are just some of the variations.
K (left), N (center and right)
You can identify the stock size without trying them on a gun. The measured "ledge" is the same for Magna stocks, Targets and Combats. With a little experience, you can tell tell the difference just by looking closely.