I have owned American Arms Derringer in 45LC /410 and the Bond Arms is much more advanced. The Ranger II is KING of the Derringer market. I have just ordered another barrel and another holster.
"WARNING- Do not use COP (copper only projectiles) in your Bond Arms Handgun!!!
They are high pressure loads with oversize projectiles that could seriously damage your Bond Arms handgun or cause bodily injury.
Bond Arms Firearms Are Not Available in Massachusetts