FUCK! I payed 50 bucks for a matrix mp5 ris. It came with some outer barrel and i didnt bother wit it. I later found out that it does not fit because of this stupid piece of metal that hooks it to the little lip that sticks out so that the back doesnt move. Its too long in its original hole. I drilled a hole and grinded it as far as it could go without destroying the small bend. the hole to put the front pin is litteraly 1mm away! I tryed drilling through it but it has a little tube that just makes my drill attempt to spin. What can I do to make it fit! The gun is the hk umarex mp5a4 btw.