Battlestate Games has put quite a lot of work on this major update, 0.12.11. The update is full of features, and after our grinding on day one, we discovered so many of them. Apparently, there is also a gun jamming feature, which might occur if the gun is damaged. Guns picked up from Scavs and Bosses are not at full durability now. Knowing the Escape From Tarkov meta, using 60-round mags will be scary to do so, especially if the “spray and pray method” occludes.
In a recent Reddit thread, a guy has tried to find the chance for this occurrence. The chance% of jamming is based on the weapon durability%. According to his experiment, the jam chance on a 100% to 95% weapon durability is quite low, but it gets scary on everything below that. His advice is to repair your gun at above 90% durability.