Most of the gun makers of years past made particular style of rifle, that was their style. Today that particular style is identified to that maker.
However each and every gun was marginally different, because each piece was hand made. Today as it was then, as a gun maker became more proficient the method of manufacture changed to the better ( in his eyes )
Also hardware availability also changed the exact contour of the gun. Some gun makers made all pieces of the gun, where as many pieces were purchased from a supplier.
All of these variables troubles us today as to why and how a style of a gun evolved.
Fred