Finding the right hardware is one thing - finding enough of it can be impossible. Here's a lot of eleven iron window sash locks that were patented in 1883 - and you can see why. These clever locks attach to your outer meeting rail only, and when you pull the grip, the spring-loaded top section swings up to let your lower window release. These eleven locks are "new-old" stock and have never been used, and they retain their original lacquer. In excellent aesthetic and working condition, this is a great find.
Antique Sash locks measure 2 3/4" wide across base(2 1/8" across screw holes) and are 1" deep. The side that flips up is 1 1/4" deep.