For the one or two readers still following along, the 1924 Belgian Proof Rule too did allow for unproved guns to be shipped directly to a Foreign Proof Facility.

[Linked Image from thumbs2.imgbox.com]

The only mark that was applied was the Rampant Belgian Lion in Heraldry:

One finds the Rampant Belgian Lion in Heraldry in the Postage Stamps of Belgium too.


Hochachtungsvoll,

Raimey
rse