I will start by saying that this is a great gun. I think it was deffiently worth the money. The bi-pod that it comes with is a good quality bi-pod so that a nice add-on. The accuracy out of this gun is respectable, but leaves something to be desired. The hop-up is a bit strange. Right now its range is good for about 100-120 feet. I don't know much about the internals, because I've never taken it apart. Lastly the inner barrel length is 470mm.