Does the mount that Magpul sells at http://store.magpul.com/product/MAG403 work with non-railed lights like the 6p? If, not is there a ring to get to attach to it?
Appears to be a no. They do pic rail mounts like the X300/X400 and the TLR-1/2/3, as well as the Surefire Scout light, which is smaller than the 6P or G2 series lights.
Impact Weapons Components makes what you want. I use them to mount my light to MOE hand guards and have seen several others.
They are simple, strong, lightweight, attractively priced, and place the light for optimal activation. All excellent.