If anyone on this Forum is considering bidding on this lot be very cautious. Personally examine the musket. The barrel has non-Springfield proofs and the trigger is not a Springfield product.
The lock is correct for a 1799 dated specimen with the rearward facing eagle. The "1799" engraved date on the buttplate return has had the second "9" refreshed.
https://bid.poulinauctions.com/RARE-1799-DATED-ARSENAL-REBUILD-OF-1795-TYPE-1_i52744685I neglected to add the photos below which are from my personal proof copy of my book.
IN RETROSPECT, I AM NOT QUITE SURE I AM CORRECT ABOUT THE HEAD OF THE EAGLE FACING LEFT. THEIR PHOTO LACKS ENOUGH DETAIL.