How are you printing it? I had the best print results, with the rail side down on the print bed and handle pointing straight up. Also what layer thickness are you set to? I don't recall having any issues printing the grooves in the handle. I don't even think it used supports for that part. I didn't create this foregrip myself, I just remixed someone elses design, and scaled it larger to fit the standard rail size. I MIGHT be able to figure out how to patch it over, but I'm no expert lol.