In February of 1943, new production Suomi submachine guns began to include a 10-point compensator built into the barrel shroud. This pattern, really the only substantial variation in Finnish military m/31 production, was identified as the m/31 SJR, an abbreviation for muzzle brake ("suujarru"). Some earlier Suomis were modified to add the brake as well. Aimo Lahti was not a fan of the modification, and there were some complaints of snow packing to the device and freezing, causing a muzzle obstruction. So my question is, did the brake actually help make the gun more controllable? I took an opportunity at the range in Finland to try both types side by side to find out...

Also, the bonus nose-to-receiver-cap shooting technique!