I am not familiar with the Heeren system and I would like to learn more about it.

I understand from previous posts, mainly originating from Kuduae, that the Heeren action was invented by Count Arturo Massa y Heeren, in 1880; patent was subsequently given to Nagel & Menz in Baden-Baden and actions made by the Suhl guntrade, first by Stephan Heym jr., then by his son Max Heym. After the patent expired the Heyms, father and son, made the rifles under their own name. Max Heym had the word "Heeren" protected as a trademark. Max Heym continued up to 1938, when he sold out to Ernst Kerner & Co. because of old age. Kerner continued to make Heeren actions and rifles until 1945.

My questions are :
• Who developped the side safety that was not visible on the initial actions, and from which year dates back this development ?
o Early Nagel & Menz action without side safety:

o Later action with side safety :

• When did the 1880 patent expired ?
• Until when was the Heeren trademark protected ?
• Where post-WW2 Glaser Heeren actions manufactured by Omega in Switzerland standard Heeren actions or was the mechanism modified by Glaser ?
• Who - apart maybe, Hartmann & Weiss and the Ferlach guntrade, manufactures Heeren actions nowadays ?
• Heeren rifles were to my knowledge originally available in 6,5 , 7 and 8 mm European calibres mostly (and by extension now in their US equivalent) but not in bigger calibres such as 9,3 (or US equivalent nowadays). Should this mean that the Heeren falling block action is not adapted to them ?
• Are there any good books or publications, in English or in German, on the Heeren system ?

Thank you in advance for any information shared.

Louis