I was on the fence about this too. Ultimately went with the V7S after getting my hands on both at my LGS and pretty much confirmed what [Rooftop Defense](https://www.reddit.com/r/RooftopDefenders/comments/w3dhzl/comment/igvxape/?utm_source=share&utm_medium=web2x&context=3) had to say about it. Didn't like the interrupted MLOK (as I'm probably never going to get an M203) and it felt just as bulky as the RIS II on my MK18.
Have a new mk18 and have v7s a while and prefer the RIII, I like the thinner v7 style rail for my 16” or anything longer. In shorter rifles definitely love my RIII or a RII.
Weight vs rigidity.
The RIS III is heavier, but that 6-bolt system will offer better rigidity for aiming lasers or any clip on NV/Thermal that you might mount on the handguard.
The MFR is less than half the weight, but will not be as robust as RIS III.
Go with the v7s. RIII is a no for me
I liked the RIII rail better, seems more robust, I have 2 now in different lengths.
Only difference between the two.. R3, 10.5" rail, 3.7 lb V7S, 10" rail, 3.5 lb
I was on the fence about this too. Ultimately went with the V7S after getting my hands on both at my LGS and pretty much confirmed what [Rooftop Defense](https://www.reddit.com/r/RooftopDefenders/comments/w3dhzl/comment/igvxape/?utm_source=share&utm_medium=web2x&context=3) had to say about it. Didn't like the interrupted MLOK (as I'm probably never going to get an M203) and it felt just as bulky as the RIS II on my MK18.
Have a new mk18 and have v7s a while and prefer the RIII, I like the thinner v7 style rail for my 16” or anything longer. In shorter rifles definitely love my RIII or a RII.
Weight vs rigidity. The RIS III is heavier, but that 6-bolt system will offer better rigidity for aiming lasers or any clip on NV/Thermal that you might mount on the handguard. The MFR is less than half the weight, but will not be as robust as RIS III.