Stronger Flak Rival Foregrip

This is a revised foregrip for CaptainSlugs' Rival Flak blaster, which strengthens the part. Firstly, It has been modified to use 10-32 screws, threaded into the aluminum u-channel instead of 4-40 screws into weak prints. Note that this will require modification of the U-channel with a drill and appropriate thread tapping tools, along with four 10-32 screws which may not come in a standard flak kit. Finally, This is modified to allow an upside-down print orientation (with print bed supports) as opposed to the slightly weaker on-end orientation that the part was originally designed for. This may have made it incompatible with worker 15-round magazines but hey, whatever, I don't use those.