Mec Gar mags are GTG and are supplied as OEM mags by many manufacturers.
Okay....you use them, then....I have no problem with that.
The Sig TACOPS 226 came factory w/4 extended “Sig” mags. The early runs of these were dreadful. Returns and replacements from the factory, same deal. Finally switched to Mec-Gars, for 9mm and .357Sig/.40S&W (they’re interchangeable) not a hiccup since.
I can’t speak highly enough about MecGar mags for the 226!