Its back, with a thingiverse friendly name!! Apparently "Gun Foregrip" doesnt work for them and they pulled it..... This will slide onto a picatinny rail and screw on tight. Once I have printed and tested I will add pictures. Also, it reaches 115 mm so make sure your firmware allows that.

The pictures are of a previous smaller version to just show the screw
UPDATE
The test print of this worked perfectly. The screw fits and the guides fit right onto a rail. I am going to make a few final revisions to the height of the core and the top pin and then it should be fully working.
UPDATE
Alright there it is: what is hopefully the final revision. It should be fully functional. If you already printed the full sized handle with the bad screw then you can just print the new screw and it should fit the handle
FINAL UPDATE
ok so i have this thing printing and it works really well. THe one issue is the screw doesnt go in perfectly and is a real pain the first time you screw it in. I probably could fix this, but its really not worth it as the overall thing still functions perfectly well. What I did is I just kept screwing it in and out until a part was smooth then i went in more. Dont worry if parts of the screw itself are peeling off...it will still work. Once you have it broken in it screws in easily and works very well on a rail.

alright so one last thing. after having my print of this working for a long time it eventually loosened up a bit much and the rail actually doesnt hold on well any more. I think that if you were to just scale down the print size by a percent or two it should stop that from happening

Just slide it on the rail, screw it on tight and you are good to go!