FF Tube Swap

[Country DeVil]

lets say I have a FF tube and I want a FF 4 rail. how easy is it to swap from one to the other? do I just unscrew the old one and screw on the new one? or is there more to it?
also anyone have any suggestions for getting a vertical grip on a FF tube?
thanks

[E53001]

buy rail sections, drill and tap the tube, now you have a bottom rail for grip or bipod, o and blue loc-tite the screws

[bkb0000]

depends on what you have on there and what you want. i assume you have one of the simple aluminum gun-show knerled tubes- if so, YHM tubes might just thread on to your existing barrel nut.. MI looks like it probably would too. you'll still need to remove the FSB, if you have one, which also requires removing your muzzle device. if you want to upgrade to professional grade, you'll need to remove your barrel nut also.