Haha, so she is asking you to put MSSA parts onto a non endorsed firearm (ie specific to that firearm), thereby creating a new MSSA without them giving you the approval prior.
My last one I had from A to E, was sitting in the safe with no pistol grip, stock or flash hider, but the AO wanted to see it complete in A-Cat form, so I had to put a thumbhole stock and thread protector on it to show it did indeed exist as a genuine A-cat and I wasn't building E-Cats from scratch.
Logical doesn't come into it unfortunately.
Moral of the story, always have a spare thumbhole stock in the safe.
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