If you consider amsec as an option, also consider sturdysafe? they are to all of the review and listed detail very .. Solid is the most apt word to describe them, I have since learned that a lot of safes sold in stores especially big name safes are rolled edge metal to give appearance of thicker stock. Big name safes stopped doing solid .25" doors in favor of wrapping sheet around drywall or other fire resistant material and other fancy stuff (edit: marketing was the word I was looking for) to make them more appealing to customers several years ago. Sturdysafe's largest drawbacks are they don't advertise so they're hard to find and they don't bother paying for UL ratings (most safes only get a UL on the lock anyways and advertise a UL rating assuming that you'll believe it's also for fire rating). The sturdy safes are also pretty well customizable in terms of how much security you want if you want fire barrier or plug holes pre drilled etc. I was actually just browsing this section of the forum to see if anyone else mentions experience with them as I am looking at purchasing the 2419 for a closet.
Some amsec is made in USA, but not sure if exclusively made in USA, I think sturdysafe is exclusively made USA.