I've tried scope boost's damage with my friend(PSG-1).Shooted his arm with scope boost and it damaged 44 then i banked scope boost and tried again the same arm and it damaged 49.I think scope boost is broken and need help with that

I've tried scope boost's damage with my friend(PSG-1).Shooted his arm with scope boost and it damaged 44 then i banked scope boost and tried again the same arm and it damaged 49.I think scope boost is broken and need help with that