Internet argument, for what it's worth.
I assume you KNOW it's wrong because you're ATF. Otherwise......
I wrote what I did because I took an AR-15 lower receiver and registered it as an SBR. However, because I selected 9mm as my caliber, and the combination model number + caliber were NOT on the list, I waited an extra month as my eForm submission was put in 'research', not pending.
Of course, I have had OTHER lower AR-15 receivers where the model number + caliber WERE on the list, and it DIDN'T go into 'research'.
Given MY experience, if the caliber and model are in the drop down list, it will be accepted, assuming all other information is correct (SN, Trust, ...). Eventually, the model+caliber that I provided were accepted. It just took an extra month........
Lastly, who do you think changes the back-end server to add those model #s to the drop down? The ATF, or the users? My money is on the ATF.
Cheers.