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? Here are some pics of the coin in question.
All I see is finning on the rim above IGWT That is due to a high pressure strike. I'm not to sure about the question you asked about it.
This one looks much different than any other S in all my other '74 mint sets. I thought it might be an old used up proof die used to make business strike coins?
I might be wrong in saying this but I don't think they have a proof die. Proof coins are made by striking the planchet more than once. Oh I just checked.. There are specially polished dies.. But I don't think they would be resused for business strike coins. Proof Coins: Are the finest quality ofcoin produced by the United States Mint. The term "proof" refers to thecoin's finish. Proof blanks are specially treated, hand-polished, and cleaned to ensure high-quality strikes. The blanks are then fed into presses fitted with specially polished dies and struck at least twice.