This is to help with identification of WWII Garand sights
The Type I Lock Bars are somewhat rare and the hardest of all sights to find, much harder than the earlier SA flush nuts. They were only used for a 5-6 month span. Last Type I sight I saw sold for $950 . These are not to be confused with the later type II and type III lock bar sights. Those sell in the $130 or less range
Type I locking bar on the right, Type III on the left (type II has same size hole, just the ends of bar are rounded)
The type I has a smaller pinion thread hole
Type I on right
The type I has a short pinion with 6-40 threads , type I & II has long pinion with 8-36 threads. As you can see the type I bar is only screwed on by a few threads.
The earlier flush nut sight uses the same short pinion but a spanner or flush nut to secure it
You couldn't disassemble the flush nut sight without a tool. The end of the combo tool (with two pins) was used for this