Thompson Center is US made.
http://www.tcarms.com/firearms/venture.php
You should be able to find the venture in .223 and "weather-shield", like stainless only more corrosion resistant.
I'd recommend the Icon, but it doesn't come in .223, .243 or .22-250 are the small caliber choices.
Savage is either US or Canada.
http://www.savagearms.com/firearms/finder/
The Savage model 16 "Weather Warrior" should do it for you.
I haven't shot that particular model, but you could check in with somebody who has I'm sure.
A new Browning is not US made.
Any particular reason that you want stainless and not blued?
Any particular reason for .223 instead of .308?
Based on your description and pointing to the GSR, you're looking for a scout rifle in .223. If you decide to jump to .308, the Savage 10 FCM Scout might fit the bill as well as the Ruger GSR. It's a nice pointable and accurate shooter in that price range.
I'll be interested to hear what you find.
Good Hunting.