Excellent lock IMO. I have two--one with Griffith's propriety hammer and one with the "common lock" hammer. I like the "common lock" hammer better. It is the same as the RE Davis/Ron Long Hawken lock hammer. The propriety hammer has a rollover curve towards the barrel for better hammer alignment with the nipple, but it doesn't look like any hammers I've seen on pictures of real Hawkens.
The Griffith lock, with it radius transition from bolster front to lock plate nose, is a style found on some J&S Hawken rifles. To my knowledge, no Sam Hawken marked rifle has this style of lock plate.
Not many other contemporary lock makers used this style of lock plate. I have a H W Robbins lock and a William Morgan lock that are this style.
The Hawken Shop in Oak Harbor, WA acquired the rights to the Griffith Tool Co. lock and breech plug and still offer it for sale. This gives you a source for replacement parts if you ever need any. Griffith locks are so well made that I doubt any part would break, but you might lose something if you disassemble it, such as the fly.
If you prefer the J&S Hawken period, as I do, you should be happy with the Griffith lock. Both in looks and function.