I have a mint set and of course there is an S LMC included. What I am curious about is that this coin looks to have proof characteristics mainly a squared rim on both sides and the features are all very crisp with fine details. I looked up if the mint repurposed old proof dies for business strikes but came up empty. Would the mint use old proof dies for making regular circulation coins? If pictures needed, I'll have to take some and post once I get home.
Proof dies have been used in the past for business strikes but supposedly by accident. This would affect the design and surfaces but I'm thinking not the rim. Being squared I'm pretty sure is the result of multiple strikes and more pressure, which would not be the case in business strikes. But as always, I stand to be corrected.
They only used reverse dies on circulation issues unless you count the SMS where they used obverse dies as well. Mint set coins are special in many ways including better hubbed dies and higher pressure for strikes. Combine all this with lots of brand new dies and it's not extremely unusual to have coins look highly PL in the mint sets.
