Depends also on how much 'rail' you plan to use and price options. A very economical way to go is the Magpul MOE hand guard. There are slits at various locations that you can add rail sections to where you want them. I have used this on my 'self defense' carbine to mount a vertical grip and surefire.
They have a different look than a full quad rail and are not free floated, but for the purpose of that rifle it is very functional. I don't need the rail space to really justify a full rail on my guns. Magpul MOE
