Gentlemen, When Pete Allen was making locks and an occasional rifle he was, as stated above by several of us, working and living in Mn. The above info is correct and he should be easy to find. He was an excellent marksman.
Re:Rear sight location-there are several original Kentucky rifles in collections across the country that have this same evidence of sight replacement or relocation on the barrel. The original location, usually above the rear ram rod thimble, was for the buyers assumed eye sight [clear site picture] as the owner advanced in age his eyes may have change thus requiring movement of the rear sight to maintain clear sight vision. This may be part of the answer in old guns but may not apply to this messed up example.
Also, Douglas barrels were all we had in a quality made product in the 60's and 70's. My two 50 year old Douglas barrels still shoot quite well. Today the problem is me !!. Be happy you have one of Pete's locks and an excellent quality barrel. Throw the rest a way or use as firewood. HIB