There are a few threads about that point to this scenario being a problem. A new firearm from S&W (with a new S/N) will need to go through an FFL. If the SKU is not on the roster can the FFL do the paperwork? A related question in my mind: what's the SKU of a bare handgun? The S&Ws on the roster are designated by SKU which seems to be associated with a combination of the handgun and original kit. Said differently, when you get a replacement handgun what's the SKU look like?

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M&P22,2x40-his
M&P22,2x9-hers