Thanks for the Link. Notice the "general" stock profile on the one from the Ambrose site is similar to yours. He dates the piece to about 1650. Could be. But I would put it a bit closer to the 3rd Quarter of the 17th Century. Notice the common three screw lock. And the small exterior screw on the tail of the lock like yours.
But IMHO the lock on your's pre-dates the lock on the Ambrose gun. It's the best "transition" style of doglock I've seen. The really wide, flat pan and the very robust frizzen on your's is really neat. I was not refering that the lock on your gun was a replacement. The entire gun looks all made together. I was just saying it is possible that your gun was assembled maybe in the Third Quarter utilizing a lock that was already made sometime in the second-third quarter of the 17th Century. I do think your gun pre-dates the fourth quarter. It's certainly the earliest doglock I've ever seen.