For me:
1 - I had to put the model number in two spots instead of one.
2 - I had to put the manufacturer of the stripped lower as the builder instead of myself. The last time, they had me put it as myself as I assembled everything.
3 - I wasn't allowed to use "Multi" as the caliber listed anymore. I had to state the specific caliber that it's going on immediately. If I wish to use another upper, I have to send in another form & have the additional caliber listed when that decision is made.

