Thanks all.
Although the BBR rifle is interesting it is the lock, not the rifle, I am curious about.
The Edward Marshall lock plate and internals are similar and engraving is close it is close to 5 3/8 inches if my notes and publications are correct. The Chambers early Germanic has a similar plate design but is larger.
Most of these on American guns seem to be from a short time period and limited geography.
I am trying to determine the size range and true proportions of this style (have not tried the golden mean but it might work for pan placement
). Have measurements from a similar lock on a pistol at 5 3/8 in length. The pistol had the English version of Number (no.) on side plate and continental furniture.
Have looked at the excellent photos on flint riflesmith's site. I did not see dimensions listed but might have missed them.
From what I can tell is the locks vary in pan style and if bridled, edge bevel and if the nose of the plate is notched which might all be finishing work differences.
I might be completely off base too!