Hello, I received a umarex hk sport line ump 45 at Christmas. Which came with a high cap mag. I've been playing with it a while and have recently started having feeding problems( ie, misfeeding, not feeding on full auto) the magazine was fully wound. So I decided to buy the ares ump mid cap. This worked ok, however did not feed as well as I had hoped, ok on semi auto but awful on full auto, I then bought another high cap, which was the same that came with the gun.unfortunatley I experienced the exact same problem immediately. I think I have come to the conclusion that the mag isn't the problem, maybe something internally within the gun. Please can someone help? Thankyou