Check the Denver quarters in your 1969 and 1971 sets closely. If they have Type-B (proof) reverses, they are quite rare. I've never found one, but I keep looking. I've read that they're out there...somewhere. Type "B" (proof) reverses on Philadelphia quarters produced between 1956 and 1964 are somewhat common. Lightly used proof dies were sometimes mistakenly used to produce business strike Philadelphia quarters. Mint marks and proofs were suspended between 1965 through 1967. Beginning in 1968, Washington quarters moved the mint mark from the Reverse to the Obverse and proof coinage moved from Philadelphia to San Francisco. Philadelphia still made all the dies and shipped them to the other Mints for use. Between 1969 and 1972, some proof dies destined for San Francisco were sent to Denver by mistake (reportedly) and used to create a small number of Denver business strikes.
The difference is so slight and look at the magnification looks like 20X I hope it's worth the problem to look through them. Also the Non Silver sets I hope you didn't pay too much over face for them. Keep hunting.
@Matthew Kruse, They have all been opened and searched. @Dean 295, I got a great price for the whole lot. Less than $100 for all but the silver bar.
There are several reverse die varieties in that span…but so the called “Type B” (RDV-002) is not one of them. The reverse you are referring to is RDV-008. You can find the reverse types here. http://www.varietyvista.com/09b WQ Vol 2/Reverse Design Varieties.htm
I buy any and all mint and proof sets I can. Cheap. Very cheap. No reason not to. Have they been searched by 15,000 people, by now? Yes. 14,996 of the searchers were looking for the bestest of the bestest shiny baubles. Good. For me. Those searchers miss the god stuff.
god stuff should have read good stuff. But, am I really spelling it wrong? Because, on this particular subject, it is synonymous, I think.