it's not a problem but when I read Sumatras won't double feed I thought something may be wrong with my rifle.
My Sumatra has always been able to double feed. Out of the box & after a full Will Piatt tune. So unless Kevin got a special one...
There's no anti double feed in the sumatra. It's just a tolerance issue. Any sumatra can be modded not to double feed by reducing hammer stroke slightly.... Meaning the magazine cycling mechanism wil only start when the moves back from shear engagement. Cycling the action until the bolt cocking screw stops against the hammer won't advance the mag, pressing it all the way compressing the hammer spring past shear engagement will.