What is it with the Sweish 12.7mm guns

I swear to god ive neevr gotten so many sparks after 100 rounds into somebodies wing then with the swedish 12,7mm guns. The 8mm are insanely better then these things. The 12.7mm are god awful like, no matter what belt I use its just dozens of sparks with maybe a lucky kill if its a biplane or something that isnt metal from a fire. 8mm are amazing, 13.2mm are great but these 12.7mm damn