Looks like a typical percussion lock from the late 1830's to 1840's to me, could be later. During the percussion era, most makers were buying locks in bulk for their guns with the engraving already on them etc. Lots of them made in Philadelphia.
You said in the original post that it was a Russell lock. does it say russell on the inside? Russell hamm made locks where made in th 60's and up to the Early 80's I've bin told. Looks like it was used alot if it's that new.