1. Only shoot the cartridges that you have personally reloaded (You could perhaps make an exception on a very trusted friend).
That way if there is a squib or double charge and you lose a finger or two you only have yourself to blame.
Back when I was working in a gun shop I knew two people who had lost fingers shooting reloads. One of the guys had lost 3 fingers ... well parts of 3 fingers. His Ruger SR9 blew up when he fired a round after a squib - tragic stuff.
The Desert Eagle is a very unique handgun ... not quite sure why it was made other than to prove you can make a gas-operated handgun... I dunno, I've always considered it the Hummer of handguns - it's big, conspicuous, and expensive to fill up.
As for the Mosquito you can tell they are made in Germany, most likely by Walther, because of the German proof stamps on the slide and the barrel. American made guns are all proofed like in Europe but I don't necessarily know of any American gun makers who proof stamp their guns (perhaps Ruger?). Oh, and Sig has a long and complicated history of ownership... Sig is Swiss then they team up with Sauer & Sohn (German) to export guns, then created an American subsidiary Sig Sauer and now it's owned by a German investment firm... something like that ... it confuses me sometimes.