Album detailing cutting the bipod legs to engage at a 45 degree angle. Shapin the back (inside) of the leg helps with a full locking position of the button. Using a flexible tape measure will help you find the center between the middle of the leg and the 90 cut from factory mark with the smaller file then start with the 1/4 file. They are aluminum so it goes quickly and easily. You could easily use a dremel if you can find your grinding drums and the drum assembly in your work bench unlike myself!
Legs are cut on both sides for a 90 so if you screw something up largely you can flip the leg so leg extension button up and still have a fully working bipod.