It would be a cool concept, but I don't think there'd be enough market for it for Glock to justify doing it, with all the other choices in that market, including their own.
A P80 G26 sized gun gets you a rail up front. A Magpul 12 rounder or factory mag with +2 gets you extended grip. And in my experience, they are also 100% reliable with G19 and G17 mags, so in a sense that gun already exists.
Bookmarks