GLOCK.
I have 3.
At
www.topglock.com. Take a G22, add a Storm Lake conversion barrel, and a GLOCK 9mm Magazine. You have a G17. 2 barrels. 1 gun. Barrels are about $ 100. And they have, some other, cool stuff.
For some reason, it appears, that Walther has a following.
I guess, I should try out, a Walther P99.