I was facing a similar dilemma not too long ago. I purchased a NIB M1D from a local collector and was having a tough time deciding on whether to open it up and enjoy it or preserve it in wraps for the next owner. Since I purchased it to enjoy, not to make money, I ended up taking mine to the range. Glad I did, but I suppose that first shot was an expensive one.
NIB M1D went for over $7800 a few years ago:
M1-D (Like NEW) SN-2743270 Auction
I suppose a gently used, well documented M1D from the DCM is still going to be worth a bit more than the sum of it's parts, and it will certainly be worth much more than what you paid for it back in 1996! Do what makes you happy - sell it and make some $$$ or shoot it and enjoy it. They really aren't that much fun sitting in the box. Take some photos so you can remember the way it was, though.
If you decide to shoot it, you may end up having to buy a new cheek pad. The leather on the one that came with my rifle was dried up and a few of the eyelets tore when trying to install it.
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