Budget aside, the TM HK 417 was born to be a DMR. Stick in a longer tight bore barrel, change the hop rubber and change the spring and spring guide and voila, 450 FPS. Of course the auto fire must be disabled but that easy to do. Either modify the selector plate as per @Rogerborg above or a Gate Titan. It goes without saying the stock TM gears will go at some point and maybe the bushes too. Essentially it becomes a money pit. But hey you can pop a zit on the nose of a speed softer at 80m.