What length free float tube do I need to cover a rifle length gas tube and block?

[jurassic]

Hi guys, What length free float tube do I need to cover a rifle length gas tube and block completely?

[Drifter]

Rifle-length handguards are usually 12.5" to ~12.75" in length, which leave the gas block exposed.

Gas block seats on the barrel usually measure ~1.9" to 2".

The typical compact low-profile gas block is ~1" in length. If this is what you plan to use, the handguard would need to be at least ~13.75" for complete coverage.

15" is a common extended-length handguard size (covers entire gas seat), and I know that DD offers a 14" rail.

[jurassic]

Thanks!!!