In a different thread, forum member Tony Williams wrote this:
source: viewtopic.php?f=71&t=118185&sid=4e4c5b6 ... 8&start=15Tony Williams wrote: ↑03 Oct 2021 13:16For example, the 7.9mm MG 17 mounted in the cowling of single-engined fighters was synchronised by means of an electrical firing system. It could therefore be described as "electric firing" but this is misleading. What happens in this case is that the synchro system sends an electrical impulse to a solenoid on the gun, which results in the firing pin being released to run forward and strike the percussion primer. The system is therefore electrically synchronised but percussion primed. In the ground role, a mechanical trigger replaces the solenoid and the gun can fire without needing a supply of electricity.
In Waffen Arsenal 166, I found these pictures:
From the German description text it appears that these MG17 were converted to fully mechanic operation only, i.e. no electric bolt release.
Any other pictures or info of MG 17 in the ground role?