"Once again, nope.Your understanding of common law is terrible"
And, for the first time:
"Your understanding of federal firearms transfer law is terrible".
As far as federal and state law is concerned, the firearms described have been "transferred" to the posessor. The transferee might not be satisfied with the commercial side of the transaction, and might challenge to be compensated according to whatever "contract" was entered into, but the "Transfer" under firearms law is a fait accompli.