The 70mm chambers suggest the gun was made after WWI BUT there is no
lettre annale, so prior to 1921.
After the Belgian proof house revisions of 1924, a
Certificat depreuve could be issued and specified:
The pressure developed, measured by crusher type device, lower or equal to 600 kg per square centimeter for sizes 16, l2, 10, 8 & 4; 670 kg per square inch for sizes 20, 24 and smaller.
600 kg/cm2 = 8534 psi maximum SERVICE pressure;
670 kg/cm2 = 9530 psi maximum SERVICE pressure
+ 10 - 14% by piezoelectric transducer measurement 12g was PROVED at 900 kg/cm2 = 12,801 psi
Modern transducer numbers would be about 14,000 psi
JNO. HY. ANDREW & CO. LTD. TOLEDO STEEL WORKS SHEFFIELD appears on high grade between the wars doubles of several Liege makers; including Verney-Carron, Jules Bury, Nicolas Lajot, L. Christophe & F. Thonon
http://www.littlegun.be/arme%20belge/artisans%20identifies%20t%20w/a%20thonon%20fernand%20gb.htm It is unclear if the tubes were manufactured in Liege or England.
