A spangled and fused AC is very likely an inspector's mark, and there are others that are not shown here, like this fused AV
![[Linked Image from photos.smugmug.com]](https://photos.smugmug.com/Belgian/Proof-Marks/i-2vFZzFH/0/MKhMVBbSM5S3xXsSsvKPx99jNx7s6B8cVJ6d8hnK3/L/Fused%20AV%20controller%27s%20mark-L.jpg)
Unfortunately, related to a fire at the Belgian proof house some marks are not recorded, and others were repeated (as shown) so can not be used to date a Belgian shotgun
![[Linked Image from photos.smugmug.com]](https://photos.smugmug.com/Belgian/Proof-Marks/i-g3ssrtv/0/NTWMgdtnC95bgXZqKsjJdBkgjJJDKkbVKs5f8gKPj/XL/BelgianInspectorsMarks%20-%20Cropped-XL.jpg)
Pete Mikalajunas' site is no more, but I was able to find and save his extensive list of tradenames and maker's marks.
There no AC in his list.
I could be of more help with a full size close up of the barrel flats and marks just forward of the flats.