Hey guys I plan to upgrade the internals on my H&K 416 by Umarex. It shoots about 350 fps and I'm looking for 400-420 fps. I would also like a faster rate of fire and if possible, a more accurate barrel that is the same length as the current one. If these were upgraded would I have to upgrade anything else in the gun as well? How much money would this cost? And what is the best quality item that isn't going to break down very fast? I would appreciate your guys' input and if any other information is needed, let me know. Thank you very much. I am new to airsoft and need a little guidance.