I believe the KW&A partnership was broken up in 1816 when TK Sr. died. William Walker died in 1819. John Adams was still alive in 1825... he probably managed the remains of the company right up until it was declared bankrupt in 1821. The only question is when did he become a partner... It was definitely after 1807. It may have been after 1812 but I don't have my notes handy and I have misplaced my photograph of the document that establishes the 1812 date one way or another. In any case, he was probably associated with the company long before that. In fact, he was probably TK Sr's brother-in-law. He was certainly a relation of some sort because his wife was a Ketland.
That said, the lock could have been sold any time up to 1821/22. I am certain they did not chuck out old stock just because of an internal marking and the general feeling I get from the period material is that after the death of TK Sr. operations were winding down. The most likely dates are some time between 1812 and 1816.