None I ever saw was. I was always able to open them just by using a knife and prying on the edges. Never had a problem taking one apart.
They were "sealed" but not always well. Yes they could be popped open with a knife blade but usualy not without showing signs of tampering. The post 1998 sets can usually be opened and closed with no trace.
crack a case out of few hundreds mint proof and silver proof set. i only got one problem case. that case was with some scratches. and three out of five coins were not in the right position. it must have been opened before and the coins being changed. so i use this one to practice it. it was successful and fun. but i don't have any to open it up again. i did found one case with a little crack. but the coins were all right. and i don't have an extra case to replace it. for the time being, that's fine for me.
2007 clad proof & silver quarters set without box & coa now i have increased my holding for 2007 clad proof & silver quarters set without box and coa. 155 set clad proof quarters set and 50 silver proof quarters set. all without box and coa. now the price have increased. clad proof quarters set without box and coa from $6.95 to $8.95 and silver quarters set from $17.95 to $18.95.
I picked up 5 1962 Unc sets yesterday at a coin show for 15.00 each I got 18.00 of spot silver in each set plus the Numismatic value of the coins
1962 set your 1962 set is only 0.61 ounce of silver per set. and it will remain near bullion for many many years. your cost is around $24.59 per ounce.
2007 quarters plan to buy more 2007 statehood clad and silver proof set without box and coa. maybe 100 set each.
box and coa now it seems that buying modern coins from dealers do not include box and c.o.a. and still they selling both with or without at the same price. and nowadays buyers seems accepting it. also note that some dealers are selling box, case and c.o.a. separately. are you willing to buy without those box and c.o.a.?.