That's dealing with honest coin shops, but you can find many out there that will try and low ball you and only offer $2 or $3 per ounce under the spot price. You can expect to get anywhere from a low of $1 per ounce under the spot price to as much as the spot price if your really lucky. Old bars that look new will only draw suspicion.As far as it's value, it all depends on your local dealers and what they are willing to pay for them. Some don't even care about the physical abuse, as buying and selling some of these bars has caused a lot of dings over the decades.Do not try and polish it or even dip it in tarnish remover. So to find one that just happened to be 7.2 troy ounces heavy is very unlikely.No one cares what a 40 year old bar looks like, it is expected to be tarnished, just not beat to crap. It's not that you couldn't find a heavy 100 ounce bar, but I've own many and they were all from the 70's and 80's and were all within one gram of the exact weight. Therefore you wouldn't know that 100 troy ounces would equal 109.714 (Avoirdupois) pounds on a quality scale. On my scale the weight it 109.72oz is it normal?Also the bar has some black spot should I bring to a jeweler to polish it to make it look mirror or just kept it as is.Also how much is a fair price to pay for this?I'm new to silver and gold just looking for some help.Thank youAssuming everything you have said is true, then everything is as it should be.Your new to Silver so you are not familiar with what a troy ounce is versus your everyday (Avoirdupois) ounce used here in the US.