For the record, I've been doing electronics since ~ 1961. Silver is indeed used for things like BNC connectors, plating on RF coils and the like. The reason is, even silver sulfide (the tarnish) is still conductive - not great, but better than open-circuit. It's a thin plating no matter what. It's only a little better (but heavier for the same conductivity) than copper. They don't use much, and now use gold on contact fingers etc, because it doesn't corrode in the first place.
At high frequencies (higher than 400hz, more like radio stuff) all electricity travels on the skin of the conductor - it's called the "skin effect" for that reason, and it's why NOTHING is made solid silver, period. It has lousy mechanical characteristics compared to other things for one. It's why ham radio operators who build their own transmitters sometimes use copper tubing - the hollow middle doesn't make any difference, and the hardcore ones then silver plate the outside.
I have a very strong suspicion that someone is mixing up milligrams (or micrograms) with kilograms here. I have for example a box you can barely lift of silver plated stuff - it probably has much less than one ounce of silver in it. And in any aircraft, weight is a big deal - they do a lot to minimize it so as to have more room for payload. I was privy to quite a bit of weapons design, and never heard of anything made of solid silver, which is what it'd take to get to those weights.
Concrete would make for a fine kinetic kill, actually, but they'd probably use something smaller and more expensive, like a carbide (like they do in armour piercing bullets). Thing is, for a kinetic kill, you have to hit the target - close doesn't really count, so that's a little suspicious too. Even the best stuff still has a CEP.
In a debate with a weapons designer I once had, who was proposing nuclear bunker busters in a circular argument, I suggested they simply orbit flying telephone poles of WC (tungsten carbide) and de-orbit them in sync over whatever they wanted to seismically crush, like pro blasters do with timed charges to make the pressure waves all add at some spot. It doesn't matter if some Iraqi is a couple hundred meters under concrete if you hit it right - the air side on the bottom spalls off concrete and destroys the contents just fine, from the shock wave. We see this also in space when something hits something else - junk flies off the far side, even at asteroid/moon sizes.
The circular argument went like this - we need it nuclear because a conventional dropped bomb won't penetrate far, and especially nukes, since they are fragile, so we need the power.
And if we do what Doug suggested, they'll think we've nuked them.
I rolled on the floor, literally - if we did what he was suggesting, we would have actually nuked them. Some argument!
Note, neither of us are in that biz now and haven't been for a long time.