Bond Arms guns are made in my hometown of Granbury, TX. I'm good friends with the guy who designed the derringer. He briefly produced a 44 Mag barrel for it, but discontinued it after a very short production run. You can probably imagine why. If you have one, you should probably hang onto it as it will only increase in value.
Also, I can assure you that the pistol is over-engineered and built like a tank. While you should not exceed pressure ratings for any firearm, some people always push the envelope. In my opinion, this derringer is designed to be about as lawyer-proof as possible.
The two reasons I don't use one as my CCW is the footprint is about the same size as my S&W 642 and Ruger LCR and heavier to boot. Plus I get 5 shots with my revolvers. It is a beautiful gun though and an excellent design.