The grade 3 forend appears to be like the early ejector forend latch, Page 147 in Brophys book has photo of this, although the forend pictured is a non-ejector forend for a hammerless gun. The unknown spring latch at the bottom is the common one used on the field guns after Hunters arms abandoned the Curtis latch.

Jim A.

I learn something every day, and a lot of times it's that what I learned the day before was wrong