I mined a bit but couldn't find exactly for what I was looking regarding the Suhl mechanics attempting to blowup the Suhl proof facility and powder was rationed to them under Russian occupation.
But I did find this thread:
>>The other guns are not mysterious at all. All the markings are shown in Gargela & Faktor's book "Zeichen auf Handfeuerwaffen" and the history is published by Hans-J�rgen Fritze in his book "Suhl - Heimat der B�chsenmacher". When the US Army took Suhl on April 3, 1945, they immediately closed down all gunmaking and sealed all shops. In the western US, British and French zones no Gunmaking exceopt for allied forces was allowed until 1951. Other in the east: On July 3, 1945 the Soviets came to Suhl. They saw things differently. The soviets wanted to make use of all production capacities of their part of Germany. In Suhl then they found several factories and about 450 independent outworkers, all in all nearly 4000 persons, sitting idle and unemployed. So on August 3 the SMATh (Soviet military administration Thuringia) ordered all the Suhl guntrade, including the Suhl government proofhouse, back to work. All the Suhl gunmakers had to produce shotguns only, no rifles, as fast as they could. All guns were to be shipped to Moscow as war reparations. The Soviets later reexported most of these guns to other countries, $$$ you know. On August 9, 1945 Russian officers accepted the first shipment of shotguns at the Sauer & Sohn company, assembled from existing parts. The Simson/BSW company was completely taken into Soviet ownership as a SAG = soviet owned stock company, starting production of shotguns on August 13, 1945. From October 25,1945 these "factories" were producing shotguns again: Waffenwerk Heinrichs; Sauer & Sohn; C.G.Haenel, Heinrich Krieghoff, Gebr.Merkel, Gebr.Rempt, Greifelt&Co, Immanuel Meffert, Friedrich Wilhelm Heym, Gebr. Heym, Chr. Funk, E.Eckholdt, F.W.Ke�ler, Fritz Kie�&Co., August Sch�ler, Ernst Kerner, Bernhard Merkel, Oskar Merkel&Co., A.W.Wolf, Franz J�ger&Co. The outworkers, stockers, locksmithes, polishers, actioners, hardeners, bluers, gun part makers and so on, again worked for one or several of these factories.
Shotgun production soon ran at high gear. All these guns had to pass the Suhl proofhouse before being shipped to Russia. In the remaining weeks of 1945 1539 guns were proofed, 21739 in 1946, 39961 in 1948. For comparision: In 1913, a very productive year for the Suhl guntrade, only 15643 shotguns passed proof.
As can be seen from your photos, at first, up to the end of 46, the Suhl proofhouse continued to use the 1940 proof stamps. There simply wasn't enough time to design, make and have approved new proofmarks, especially for political considerations. For 1947 new proofmarks were finally introduced, consisting of the "pick and sole" of the Suhl city crest, topped by the letters M,N or SP. The 15/DR/1 in an oval was the then code for the Suhl proofhouse authority. As there was no shotgun ammo production in eastern Germany then, the proofhouse had to make do with Russian-made proof cartridges supplied by the Soviets. As these cartridges were of very variable quality they sometimes missed the German, later CIP standards for nitro proof pressure, so the SP = black powder proofmark only was applied, in spite of the proofloads being smokeless. The Soviets, the only customers, did not care about this nicety.
In 1951 the new-founded GDR gained control over the guntrade and introduced "new" proofmarks, a simplified form of the 1893 -1939 ones. From 1974 on they again used marks very similar to the 1947-1950 ones.<<https://www.doublegunshop.com/forum...ds=proofhouse&Search=true#Post288666