What you have is a lock from a U.S. Model 1816 smoothbore musket. Some gun scholars refer to it as the Model 1822. This particular lock was originally flint and was probably converted during the 1840's to early 1850's. P & E.W. Blake were nephews of Eli Whitney, Sr. and were actually made trustees of the Whitney Armory upon his death in 1826, Whitney's son Eli Jr. being too young to take over the operation. Their names appear on the locks of Model 1816 muskets made under the 1822 contract made from 1826 till Eli Jr. reaching his majority. So, apparently your lock was from a piece from that contract. The locks of these muskets were marked between the cock and frizzen spring "US" and "P. & E.W. BLAKE, and behind the cock "NEW HAVEN" in a curve and a date, in your case, 1827, reading to the rear in two lines. By 1835, they resumed the use of the Whitney name instead of Blake. If your lock was converted to the Maynard tape priming system which many 1816 muskets were, it would have been done after Sept. 1854. Thousands of these muskets saw service in the Civil War on both sides, and of course were the standard infantry weapon in the Mexican War. Actually, I would also look closely at the barrel, if it is a 16 gauge (.69 cal.) and 42" long, it could be the original barrel, of course it may have been cut down. Look for proof marks about the breech. Springfield and Harper's Ferry Model 1816 barrels were marked "P" in an oval, "eagle head" and "V". I believe that contract muskets were marked the same (at least ones that I've seen)as they had to undergo the same inspections by U.S. Armory inspectors. These marks may have been obliterated by rust and/or cap flash. Also, there was more than likely the date of manufacture/inspection. At least on National Armory pieces. The bayonet stud on this model was on the top of the barrel, 1 1/4" from the muzzle. Sounds like you made a good find. Another thing about this lock, with the exception of using filing jigs, this was a handmade lock. The parts were forged then finished by lock filers.
I hope this helps you a bit. I wish I could run across something like this myself.
:thumbsup: :applause: