A so-called Rouxdrilling with coilsring-driven striker lockwork is very unusual in the first place! Can you please post photos of thesr locks? As I know the Zella-Mehlis makers, who catered to the lower-price market, I doubt they used square coil springs originally. An old German Drilling with problems igniting the rifle cartridge is a frequent occurence, often subject of questions to the GGCA. This applies more often to hammer drillings. On these a lower part or neck of the right hammer hits a transfer bar, which in turn drives the firing pin/striker at an acute angle into the primer cup. But in their days these Drillings were reliable shooters. Reason: the old German cartridges used Berdan primers of a large, 5.5mm diameter. The primer cups were made of soft copper. They were much more easily dented than today's large rifle primers. A firing pin blow that was marginally effective on German primers of the times around WW1 is plainly insufficient for modern large rifle primers. Here in Germany a often used remedy is using large pistol primers in 9.3x72R cases, which are more easily dented than lr ones. At the low pressures allowable in the 9.3x72R, much less than in a .44Mag, this is an option.