Stick to military calibers like .308, .223, .45, 9mm. You will always have a source for ammo. Second, look at the Remington 700 in .308 and the Remington 870 for 12 gauge. Next, Ar-15 for .223, there more reliable than people think and parts are plentiful. For pistols, look for a 9mm or .45 or both,...