Hey ladies and gentlemen I’m new to the airsoft scene, Bought myself a new Specna arms c11 core, straight out of the box I was experiencing feeding issues firing .20 bbs and even .25 every 5-6 shots that’s when a bb would come out. I noticed the hop-up was a little loose, you could move it sided to side about 3-4mm each way. So I ended up fixing the issue by putting a O-ring on the front of the hop-up to stop it moving “BINGO” all fixed with zero feeding issues now works absolutely perfect.