The Radian Weapons AR15 Takedown Pin Kit will work with an FN15 DMR III.
Radian Weapons AR15 Takedown Pins are precision CNC machined steel. However, the specifics of the steel are not provided by Radian. I'd recommend reaching out to them directly for more information.
No, the HK MR556/MR762 use a proprietary rear takedown pin.
Yes, these pins will be compatible with the 15-22.
These are made from precision CNC machined steel.