exaggeration aside, a large jewelry safe could probably handle that many OZTs of silver. they are so heavy that they cannot be easily moved by the common thief. we just bought one from a JC Penny liquidation for a few hundred dollars (the safe movers said that they typically go for about $1700 used). It is about 4 foot by 4 foot and weighs thousands of pounds. the expensive part is hiring someone to move it.
I personally love the idea of having a safe full of coins and other valuables. Only problem is that I don't have a safe, a house or enough coins to fill a safe. I was strongly considering buying silver bars, but I don't understand why they all have serial numbers on them. Plus, how do you know there isn't a core of lead in them. difficult to trust PM bars.
Serialed bars are less likely to be counterfeited because you can look up the serial, same with slabbed coins. Sure, it can happen. The majority of my bars were purchased from the mint that created them so no worries there. The rest I purchased from coin shops, serialed bars only. Government issue coins are easier to verify which is partially why they have a higher premium. A lead core wouldn't weigh properly. A lead/copper alloy could fool a lot of tests though. It's important to buy from trusted sources.