There is some duplication here. Altogether we only have 5 named patterns.
This is Belgian Laminated or Twist. It is 50% iron / steel. Notice the broken or segmented steel layers. This gives the impression that there is less steel in the barrel than there actually is when it is twisted.
All the sample boxes in the world are still meant as salesman's tools. The only standardization would be in the Belgian naming of those patterns that were patented. These are the only surviving images from those patents. Everything else is lost to us at the moment.
Unless some is willing to go as far as Manfred Sachse did, we will never be sure of all that is involved in assembly of the billets.
Pete
