Homemade Gun: Titanium .45 Colt & .410 Over/Under Pistol ECCO Machine Published on Oct 6, 2016 A one-of-a-kind double barrel big bore pistol, chambered for .45 Colt & 3" .410 shells. It is an internal hammer design, not far removed from many over/under shotguns, but yet with some distinct differences. Perhaps one of the features that sets it apart most is that it is almost entirely made from 6Al-4V Titanium and 7075-T651 Aluminum with Carbon Fiber for the grip panels. The only steel is the barrels (1026 alloy) and small parts (D-2 tool steel). Weighing just 46 ounces, it's pretty light for it's size, but heavy enough that it's fairly pleasant to shoot, even with hot .45 Colt loads that duplicate .44 Magnum performance.