updated the
gaunt page, with, what I think is the current opinion on the "gaunt dots" and "no dots" saga. (this actually makes sense now - to me anyway)
I think the small variations in length we arrive at when measuring these marks is due the the degree of bulging out of the metal when the stamp displaces the brass, which will depend on the force it's struck with.
anyway, seems to be consistently 15mm and 11mm plus or minus 0.5mm
have also added a 'gaunt, late jennens' onto that page as well, courtesy "Gurkha"